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NOTES ON PATENTS. 
LIFTING MACHINERY. 
BEAMS AND PILLAKS. 
STRENGTH OF METALS. 
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MACHINES AND TOOLS EMPLOYED 



WORKING OF SHEET METALS. 



BY 

R. B. HODGSON, A.M.INST.MECH.E. 

Author of "Emery Grinding Machinery." 



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1903. 
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ERRATA. 



On page 63, line 11, instead of "the limiting diameter, &c.," read 
" The minimum diameter of any hole in a plate t inches thick of any 

material is 

_ t x 4 x the limiting shearing strere 
crushing stress of punch 

On page 94, fig. 96, dimension of base should read "4Jin.." not 
"4ft Sin." 



PEEFACE. 



THE scarcity of the literature on Presses and Press Tools is in itself 
sufficient justification for the publication of these articles, which 
appeared originally, at intervals, in the columns of The Practical 
Engineer, and are now published in book form at the request of many 
readers. 

The production of tools for the working of sheet metals is a distinctly 
separate branch from that of engine-fitting and general machine work. 
It is therefore difficult for an engineer to thoroughly grasp the work 
of the press-tool maker, unless he has had an opportunity of closely 
watching the tool work in progress and the subsequent operations 
performed by the tools in tha production of numerous articles made 
from sheet metals. 

This difficulty is largely due to the many technical points of detail 
connected with the processes through which an article may have to 
pass before reaching its final stage, which will become obvious upon 
reading Chapter XI. Drawing and Re-drawing and Chapter XIX. on 
Tool Setting. 

The subject embracing, as it does, many industries, including a vast 
number of separate processes, no systematic treatment has been 
attempted. As far as possible each section has been taken separately, 
and where necessary to a complete and thorough understanding of a 
point under consideration, either a little recapitulation has been deemed 
advisable, or reference made to the chapter or section where the 
particular point has been previously mentioned. 

The original articles were the result of many years' work, and study 
of a business which plays an important part in many British industries, 
and it is hoped that these collective notes in book form will be found 
useful to engineers, mechanics, manufacturers, and to young technical 
students, assisting them to overcome some of the difficulties which 
they may meet with in technical schools and workshops. A few 



VI. PREFACE. 

remarks in reference to the machine tools to be found in every machine 
shop have been included, to enable the younger readers to better 
understand the matter contained in those chapters which refer to the 
manufacture of press tools. 

At present very little seems to be known by mechanics in the work- 
shops concerning the work done in either a Fly Press or Drop Stamp. 
It is therefore hoped that the special chapter devoted to the following 
subjects work done in Copying Press, Fly Press compared with the 
Screw Press, work done by the Stamp Hammer, the reasoning regarding 
the Hammer Blow will be readily followed by the student and 
practical mechanic, who may not have sufficient scientific and mathe- 
matical knowledge to follow the reasoning of the more advanced 
text-books on the subject. 

The illustrations used are of a special character, and do not represent 
every possible type of Power Press. Those selected may be regarded as 
being good practical examples of modern machines and calculated to be 
useful to the greatest number of those who are engaged in sheet-metal 
working industries. 

Calculations and definitions have been introduced to enable practical 
mechanics to readily grasp the point under consideration with tin* 
least possible calculation, and at the same time more accurately and 
quickly than by " rule-of -thumb " methods. 

Any suggestion relating either to improvements or additional matter 
calculated to make this work more complete will be gladly and care- 
fully considered, with a view to the revision 'of future editions. 

The Author takes this opportunity of thanking his numerous friends 
for their valuable assistance, specially mentioning Mr. Daniel Smith, 
whose information regarding both machines and tools has greatly 
assisted him in his work. The Author's best thanks are also due to 
Messrs. Buck and Hickman, London ; Daniel Smith and Co., Wolver- 
hampton ; John Rhodes and Son, Wakefield ; Taylor and Challen Ltd., 
Birmingham ; W. H. Ward and Co., Birmingham, who, by their 
kindness in placing at his service electros of special machines have 
enabled the text to be illustrated so as to make it more readily under- 
stood. 

R. B. HODGSON. 

54, Westfield Road, Kings Heath, 
Birmingham, 1903. 



CONTENTS. 



CHAPTER I. MATERIALS AND MEASUREMENT. PAGES 

Introduction Metal Gauge Tables Common Sheet Brass Best Dipping 
Metal Alloy Suitable for Cartridge Cases Worthless Gauges Imperial 
Standard Wire Gauge Whitworth Standard Old Birmingham Wire 
Gauge ...1-7 



CHAPTER II. -MICROMETER GAUGES. 

Brown and Sharp Micrometer Pitch of the Screw Graduations ou the 
Thimble Reading the Micrometer Micrometer Rolling Mill Gauge- 
Plate Gauges Internal and External Gauges Standard Cylindrical 
Gauges Limits of Accuracy Metal Work Defined Terms Used for 
Various Presses Operations Defined by Terms 7 21 



CHAPTER III. THE SCREW PRESS. 

Example of Double-sided Ply Press Details of Screw Press Gartering the 
Ram Formation of the Gartering Nut Various Methods of Gartering 
The Bumping Bit 2130 



CHAPTER IV.- FORM OF SCREW PRESS FRAME. 

Frame Casting Screw-cut Frame Casting Bored to Receive Special Nut in 
Large Work Strengthening Stay Rod Strengthening Press Frame at 
Back Position of Stresses in Press Frame Method of Strengthening 
the Weakest Point of Casting The Press Screw Formation of Screw 
Thread Threads and Spaces Compared Faults Due to Pitch of Screw 
Multiple-threaded Screws 30-i 



CHAPTER V. A POWER PRESS. 

Example of Power Press -Details of Working Parts Methods of Driving the 
Ram Gear for Guiding the Driving Belt Adjusting the Ram by Means 
of Plates Faults of Cast-ircn Clutch Driving by Means of Steel Pin 
Through Fly Wheel-Example of Steel Pin Clutch-gear and Counter 
Shaft ... 38-45 



viii. COST i 

(I1APTEK VI. FAULTY CONSTRUCTION. PAGE* 

Four Ham* ojvrnte.l Simultaneously Faults in Construction Unreliable 
Mctho.1 of Erecting Faulty Method of Driving Ram Direction of Shaft 
Rotation-Forces Acting on Ram-Relative Position of Cranks Coupling 
tin- Two Crank Shaft 4552 

CHAPTER VII. DIM AND PUNCHES. 

Forging a Stamp Die The Solid Steel Die- Die having Wrought-iron Base- 
Examples of Cylindrical Die and Rectangular Die Careless Hardening 
Per Cent of Carbon in Tool Steel-The Upper Die or Stamp Force- 
Methods of Attaching Force to Stamp Hammer -Formation of the 
ForcePunching and Shearing Formulae Theoretical Limits of Thick- 
ness that may be Punched The Angle of Dip on Shears -Punches Built 
up in Sections Methods of Fixing Punch -Action of Punching and 
Shearing-Parallel and Screwed Shank Compared - Methods of Fixing 
the Bolster-Methods of Fixing Cylindrical Die-Interchangeability of 
Die and Punch 5279 

CHAPTER VIII. ACCURACY AND DURABILITY. 

Standard Dies and Punches Preparing a Standard Die Correcting the Die- 
Preparing the Punch Interchangeable Tools ..80 86 



CHAPTER IX.-DU MAKING BY DRIFT. 

Formation of Drift Preparing the Die for Drifting Complete Set of Piercing 
Tools Stripper and Guide Plates Automatic Knockout or Flipper 
Blank Cutting Tools-Special Drill Chuck-Automatic Umbrella 
Stretcher Machine-Construction of Cropping Die 37-106 



CHAPTER X. MKTAL SPINNING. 

S],iimii>K ornamental Work Spinning a Rivet Head- Spinning a Sheet Steel 
Cup-Special Form of Chuck Extracting Mechanism Actuated by Ram 
Setting the Extracting Mechanimn Tools for Bending Wire Form of 
Tools for Metal Beudlng-Press Tools for Wire Cutting 106-120 



CHAPTER XI.-DRAWIN.: AM. UK-DRAWING. 

Radius on Drawing Punch End Tool Dimensions for Re-drawing Drawing 
a Metal Sphere Formation of Cartridge Shell Successive Piercing and 
Blanking -Stamping a Steel Washer-Combination Tools -Construction 
of Double-action Press -Attaching Punches in Double-action Press- 

Heinoving Siinll Shell from 1 irawing I'um-h 127-148 



CONTESTS. ix. 

CHAPTER XII. PRESSES FOR SPECIAL WORK. PAGES 

Election of a Suitable Power Press Important Points in Press Construc- 
tion The Use of a Stay Bolt on a Press Single-acting Power Press- 
Geared Single-acting Press Chief Defects in Single-acting Press Single- 
acting Open-back Press Pressure Plate with Positive Lift -Ad justing 
the Pressure Plate Advantage of Balanced Slides 149167 



CHAPTER XIII. DOUBLE-ENDED PP.E.-SSES. 

Tool Changing in Double-ended Press Stop Motion Arranged in Ram- 
Proper Place to Apply the Stop Motion Dangers of Sliding-key Stop 
Motion-Details of Metal Shearing Machines -Shearing Machine for Cir- 
cular Blanks Cutting Blanks by the Shearing Method 168181 



CHAPTER XIV. ROLLER AND DIAL FEED MOTIONS. 

.Advantages of the Roller-feed Motion Construction of Dial-feed Motion- 
Details of Dial-feed Motion Important Points concerning the Dial 
Plate Application of Roller-feed Motions Accidents to Operators' 
Fingers Unexpected Descent of the Ram Worm Adjustment for the 
Ram Toggle Drawing Press Armature Disc-notching Machine Feeding 
Blanks by Vertical Hopper 182-203 



CHAPTER XV.-STAMPINO. 

The Ordinary Stamp Weight of Stamp Block and Hammer Advantages of 
the Double Stamp Accidents to Stamp Operators Automatic Drop 
Hammers Details of Automatic Drop Hammer Stamp Hammer Raised 
by Friction 204-214 



CHAPTER XVI. AUTOMATICS AND MACHINE TOOLS. 

Selecting Special Automatics Machines Used for Tool-making Lathe for 
Boring a Stamp Die Screw-cutting a Punch Shank The Use of a 
Shaping Machine General Purpose Drilling Machine Method of Drilling 
a Cutting Die Use of the Profiling Machine Profiling a Cutting-out 
Bed Special Machine Vice Quadrant Dividing Head Stocks 215235 



CHAPTER XVII. TOOLS AND JIGS FOR REPETITION WORK. 
Types of Lathe Test Indicators Method of Applying Test Indicators 
Accurately Boring Tools and Jigs -Accurate Methods of Drilling by Jig- 
Setting Work upon a Lathe Face Plate 236-246 



CHAPTER XVIII. INTF.RCHANGEABLE MACHINE PARTS. 
Preparation of an Accurate Boring Jig The Use of a Boring Jig 246251 



X. CONTENTS. 

CHAI'TKR XIX. I'KKSS TOOL SKTTINO. PAOKS- 

,.f C,.rm-t Tool Suiting- Troubles Caused by Careless Tool Setting- 
Cointnoii Stripjier Arrangement!* and Waste Work Correct Setting of 
Punch, Bed, and Stripper-The Stop Teg on a Cutting Bed-Guide Plate 
Fixed to Cutting Bed -Hardening and Teni]*riug- Heating Steel 
Uniformly for Hardening Hardening and Tempering at One Heat 
Hardening and Tempering Dies and Punches Hardening and Temjier- 
ing a Slitting Haw Annealing Sheet Metals Table of Colours for 
Tempering-Annealing Dies and Tools-Annealing Dies in Slaked 
Lime... 251273 



CHAPTKK XX. BLANK DIMENSIONS. 

Three Methods for Fixing Blank Dimensions-Mensuration of Sheet metal 
Surfaces Measuring an Article in Sections- Clipping of Stamped 
Articles.... ....274-286- 



CHAPTER XXI. PRESSURES FOR CITTIXG BLANKS. 

Pressures Required to Shear Iron Bars Factor of Safety for Shearing 
Machine Definitions of Terms The Power of Presses and Stamps- 
Work in the Copying Press - Work of Fly Press Fly Press Compared 
with Copying Press Work Done by a Stamp Hammer Accumulated 
Energy Stored in Hammer 2S..-302: 



MACHINES AND TOOLS EMPLOYED 



WORKING OF SHEET METALS. 



INTRODUCTION. 

FOR some years past the author has experienced a constantly- 
recurring need of a practical treatise on this important class 
of machine tools, as well as of the processes used in the 
working of sheet metal, and has found that English writers 
on mechanical subjects appear to have generally neglected 
this branch of engineering. It is true that in describing 
certain processes incidental references are made to some 
special form of press devised by them, yet there does not 
appear to be any treatise dealing with the subject in a 
systematic manner. American writers also have apparently 
neglected this subject, save as a subsidiary section of a work 
dealing with other branches of mechanical engineering, and 
then only in books which are published at a price which is 
generally prohibitive to the ordinary mechanic or student, 
whose means are limited. 

A possible reason for this general neglect may be found 
in the multiplicity of articles that are now being manu- 
factured from sheet metal, each of which possesses its 



2 MACHINES FOR SHEET METAL WORK. 

own individual shape, often involving a large number of 
steps or operations before it is attained. Thus it has become 
to a very large extent a branch of engineering that does not lend 
itself to a systematic treatment like many others, except at 
the hands of a specialist. The author has devoted many 
years to this branch of engineering, in which, in addition to 
operating the presses when made, he has had frequent occasion 
to design both the press and the tools required by it for 
special purposes. In consequence of the lack of any text- 
book of reference, he has found himself constantly going over 
the same ground as other engineers had previously, 
entailing in consequence the loss of much time ; hence he 
ventures to think that in collecting together the knowledge 
obtained in his own practice, supplemented by an account of 
the results that have been already achieved in the use of 
these important labour-saving machines in the reduction 
of the costs of manufacture, a useful work will be the result. 
A systematic treatment of the subject seems impossible, 
so no attempt will be made in this direction, but a descrip- 
tion of one or two generally used presses will be dealt with 
at first, showing how the simpler results are obtained, 
afterwards passing on to the consideration of the more 
complex operations, in which more than one stage is 
required to complete the work. By thus gradually building 
up from the simple form to the more complex, it is hoped 
that the reader will be able to follow along easily the 
gradual development of a most interesting class of tools, 
which the author ventures to think will he appreciated more 
and more by engineers, who are being pressed hard to 
produce cheaply everything that they manufacture in order 
to hold their own in the commercial race. 



MATERIALS AND MEASUREMENT. 



CHAPTER I. 
MATERIALS AND MEASUREMENT. 

THE metals in general use are sheet brass, copper, tin plate, 
iron, and steel, rolled to the required thickness before 
reaching the workshop tojbe cut intojjlanks and formed into 
the required shapes. In most cases the Various metal alloys 
a7eTmixed~according~to the requirements of the manufacturer, 
but for brass work a commercial metal is in use known as 
"Best dipping metal/^this being mixed so as to be most 
suitable fur_ dipping or gilding. Further, the metal known 
by this name stands more torturing whilst being worked 
than the ordinary common sheet brass, the reason being that 
it contains a greater percentage of copper. Some of the 
most important articles produced from brass are ammunition 
cases, which require a special alloy, as well as great care and 
judgment in arranging the number of processes and anneal- 
ings, to enable the case to be worked into shape without 
rupture. The proportion of the metals forming the alloy 
suitable for cartridge cases is 70 per cent copper and 30 per 
cent zinc. 



The metal sheets are usually measured or gauged b 



by a 
nifty 



win- or metal gauge. There are between twenty and thirty 
(Efferent wire or metal gauges in actual use, each gauge 
being considered by some manufacturer as the standard 
gauge that should be used for their own particular work. 
There appears to be no reason why one standard gauge 
should not be used throughout the whole industry, and if 
this could be arranged, much loss of time, trouble, and 
inconvenience to which manufacturers are now subject 
would be prevented. Many of the gauges now in use are 
practically worthless on account of the misleading and 
peculiar manner in which their sizes run. The appended 
table represents the gauges most frequently found in use by 
the trade. 

It is customary to speak of the thickness of a sheet or 
wire as, say, No. 7 gauge, which means that the thickness is 



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6 MACHINES FOB SHEET METAL WORK. 

that represented by the width of a slot against that number 
in some gauge. These numbers are given in the first column 
of the table, and the actual thickness in terms of an inch 
will be found for the several gauges in their respective places. 

The second column (B) gives the values for the Imperial 
standard wire grange, which is the legal standard in this 
country by the Weights and Measures Act of 1878, and as a 
consequence no contracts or dealings can be legally enforced 
that are made contrary to this standard. 

The South Staffordshire Ironmasters' Association held a 
meeting in Birmingham on the 28th February, 18St, : ui<l 
by resolution adopted as their standard that shown in 
column H. 

In column D is shown the proposed standard by the late 
Sjr__Jo8eph Whitworth,_which is, as far as one can see, the only 
rational system contained in the table. It should be noticed 
that the number of the gauge is also the number of 
thousandths of an inch that measure the actual thickness 
of the sheet. It ought also to be noted that as the numlxjr 
of the gauge gets greater so does the dimension increase, 
whereas with the other standards the higher numbers have 
the smaller dimensions. The true solution of the gauge 
question appears to be in the adoption of the Whitworth 
standard, and in place of the present misleading plate 
gauges the general adoption of a micrometer graduated to 
read to T ffVzr f au i ncQ f r the determination of the actual 
gauge in each instance. 

The old Birmingham wire gauge, which can be traced 
lick for 45 years, is shown in column J, and the figures 
shown in column K refer to that known as the Birmingham 
metal gauge. 

The gnuges as per columns B, C, D, F, H, J, K, L are all 
in use. Manufacturers who roll metal for the tnvde have, 
consequently, an understanding with each of their customers 
as to which gauge their metal must be rolled to, and this 
makes it necessary that each lot of metal ordered be pmood 
through the rolling mills in a separate batch. 

A few moments' consideration will suffice to show how the 
use of these different gauges cause troubles and inconvenience 
to manufacturers. It seems that the only course open to 



MICROMETER GAUGES. 7 

manufacturers generally is to fall in line with the require- 
ments of their customers upon the gauge question. 

The figures given in column L are those of the American 
standard wire gauge. The want of uniformity in common 
wire gauges led the Brown and Sharpe Manufacturing Co., 
at the request of the principal American wire drawers and 
brass workers, to prepare this standard, which was worked 
out so that the variation between the different numbers on 
the wire gauge should not be so irregular as those numbers 
oil" the Stubs wire gauge. Previous to the introduction of 
this new American standard the Stubs, gauge was_ the one 
generally used in America, but the Brown and Sharpe gauge 
has now taken the place of the Stubs gauge in America. 
The Brown and Sharpe Manufacturing Co., as gauge makers, 
have earned their reputation for high-class work, in accuracy 
and finish, and a special feature of their wire gauges 
worthy of attention is that, in order to familiarise the 
users of the gauge with the decimal equivalents of the 
gauge numbers, they stamp on the back, opposite to the 
regular gauge numbers, the decimal equivalents expressed 
in thousandths of an inch. 



CHAPTER II. 

MICROMETER GAUGES. 

THE Brown and Sharpe micrometer gauges form convenient 
and accurate tools for external measurements. They are 
made in various sizes and styles to measure up to 24 in., and 
are graduated to read English measure to thousandths and 
ten-thousandths of an inch ; they are also made to read 
to hundredths of a millimetre. The decimal equivalents 
stamped on the frame are convenient for the immediate 
expression of readings in eighths, sixteenths, thirty- seconds, 
and sixty-fourths of an inch. 

The chief mechanical principle embodied in the con- 
struction is that of a screw free to move in a fixed nut, an 
opening to receive the work to be measured is afforded by 



8 MACHINES FOR SHEET METAL WORK. 

the backward movement of the screw, and the si/e of the 
i>lM'iiingis indicated by the graduations. 

Referring to fig. 1, the pitch of the screw C is forty to 
the inch, the graduations on the barrel A, in a line parallel 
to the axis of the screw, are forty to the inch, and figured 
0, 1, 2, etc., every fourth division. As these graduations 
conform to the pitch of the screw, each division equals the 
longitudinal distance traversed by the screw in one complete 
revolution, and shows that the gauge has been opened 
one-fortieth or twenty-five-thousaudths of an inch. This 
opening (between B and C) in fig. 1 is three divisions 
exactly, and is therefore = 3 x 140th of an inch, or 
seventy-five-thousandths. 

The bevelled edge of the thimble D is graduated iito 
twenty-five equal parts, figured every fifth division, 0, 
5, 10, 15, 20, each division, and when coincident with the line 




Pio. 1. 

of graduations on the barrel A, indicates that the gauge 
screw has made one-twenty-fifth of a revolution, and the 
opening of the gauge increased one-twenty-fifth of twenty- 
five-thousandth = one-thousandth of an inch. 

Hence to read the gauge, multiplv the number of divisions 
visible on the scale of the Iwirref A by 25, and add the 
number of divisions on the scale of the thimble D, from 
zero to the line coincident with the line of graduations on 
the hub. For example, as the gauge is set in the figs. 2 
:tnd ." there are three whole divisions visible on the barrel ; 
multiplying this number by 25, and adding five, the number 



MICROMETER GAUGES. 



of divisions registered on the scale of the thimble, the result 
(3 x 25 - 75, then 75 + 5 = 80) is eighty-thousandths 
of an inch. After a little practice these calculations are 
readily made mentally. 




The micrometer is shown full size at fig. 2, and measures 
all sizes less than an inch by thousandths of an inch; 
whilst the micrometer shown by fig. 3 is graduated to read 



10 



MACHINES FOR SHEET METAL WORK. 



to ten-thousaudths of an inch. Upon the ends of the 
screw (', and tin- face of B, falls all the wear due to actual 
use, and in order to provide for this, B is a tightly fitting 




screw, which may he advanced from time to time as 
required. The slot for the screw-driver is shown to the 
left in figs. 1, 2, and 3. Thus, every gauge ought always 



MICROMETER GAUGES. 



11 



to read accurately the dimension of the opening between B 
and C, no matter how constantly they are in use. The 
readings of ten-thousandths of an inch are obtained by 
means of a vernier, or series of divisions on the barrel of the 
gauge, as shown in fig. 4. These divisions are ten in 
number, and occupy the same space as nine divisions on the 
thimble, and for convenience in reading are figured 0, 1, 2, 
3, 4, 5, 6, 7, 8, 9, 0. Accordingly, when a line on the 
thimble coincides with the first line of the vernier, the 
next two lines to the right differ from each other one-tenth 
of the length of a division on the thimble, the next pair of 
lines in order to the right differ by two-tenths, etc., as 




II] 

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,11111111 ,Mj 

1 I 1 _[ I II I] I 

o in 

THIMBLE 



shown by the upper illustration of the two enlarged views of 
the graduations on barrel and thimble. Since each of the 
divisions thus measured are equal to one-tenth part of a 
division on the thimble, it follows that they are each equal 
to one-tenth of one-thousandth of an inch i.e., one ten- 
thousandth of an inch. Hence, when the gauge is opened 
the thimble is turned to the left, and when a division passes 



12 MACHINES FOR SHEET METAL WORK. 

a fixed point on the barrel, it shows the gauge has been 
opened one-thousandth of an inch. Hence, when the 
thimble is tumed so that a line on the thimble coincides 
with the second line (end of the first division) of the vernier, 
the thimble has moved one-tenth of the length of one of its 
divisions, and the gauge opened one-tenth of one-thousandth, 
or one ten-thousandth of an inch. When a line on the 
thimble coincides with the third line (end of second division) 
of the vernier, the gauge has been opened two ten- 
thousandths of an inch, etc. 

In the lower diagram of the vernier in fig. 4, where the 
fourth line marked 10 on the thimble coincides with that 
on the barrel marked 3, which is the third division of the 
vernier, shows the position which indicates three ten- 
thousandths of an inch. To read this gauge, note the 
thousandths as usual, then the number of divisions on the 
vernier, commencing at 0, until a line is reached with which 
a line on the thimhle is coincident. 

If the second line reached is figured 1, add one ten- 
thousandth, if it is figured 2, two ten-thousandths, etc. 
Gauges graduated to read to ten-thousandths should not be 
used on ordinary fine mechanical work, as in instruments of 
this class wear perceptibly affects the readings, which would 
be of comparatively slight consequence in gauges reading 
only to thousandths. These gauges should therefore only 
be used as a final test for very important accurate work, 
and their use requires a much more delicate sense of touch 
than in the case of the thousandth gauges to obtain exact 
readings. For such fine adjustments, these gauges are often 
fitted with a friction clutch for moving the screw, so that 
the same degree of tightness is always obtained. This is 
very important when measuring substances that are soft and 
easily indented to the extent of one ten-thousandth of an 
inch. 

MICROMETER ROLLING MILL GAUGE. 

A micrometer gauge, which has recently been introduced 
for the use of sheet metal workers, is shown by fig. 5, and it 
is well adapted for this class of work. The gauge screw is 
encased and protected from dirt or injury, and means of 



MICROMETER GAUGES. 



13 




14 



M \ II INKS Foil SIIKKT \IKTA I U OBK. 




PLATE GAUGES. 



15 



adjustment are provided to compensate for wear. The open- 
ing in the frame is about 6 in. deep ; this is a very important 
feature, as it enables sheet metal to be more accurately 
measured than would be possible with an ordinary micro- 
meter. This great depth in the frame makes it possible to 
measure or gauge the metal at various points in the width 
of the sheet, which could not be reached with the ordinary 
pattern of micrometer gauge. 

The British standard wire gauges in three patterns are seen 
at figs. 6, 7, and 8 the oblong, the double circular, and the 
single circular respectively. The American standard wire 
gauge shown in fig. 9 is that gauge adopted by the American 




brass manufacturers, January, 1858 (see the figures given in 
column L of gauge table), in place of the Stubs wire gauge. 
This American gauge, as previously mentioned, has the 
decimal equivalents stamped upon the back in thousandths 
of an inch. 

This pattern of gauge is much inferior to the micrometer 
type. It is not always clear which of the several standards 
they actually represent, whilst as often as not the faces of 
the openings are anything but parallel, and in consequence 
there is some choice left to the user to determine which place 
gives the actual gauge. They serve, however, as a rough 
guide to the thickness of the plate or the diameter of a 
wire ; but it must be borne in mind that measurements made 
by it can only be approximate at the best, for it is quite 



it; 



MACHINES FOR SHEET METAL WORK. 



impossible to determine how much larger or smaller a plate 
or wire is than the nearest opening that may be found in 
the gauge. it is to be noticed that there is no way of 
taking up the wear that must inevitably result after the 
gauge has been in use for a time. 

IXTKUXAL OR EXTERNAL GAUGES. 

The standard internal and external cylindrical gauges, 
fig. 10, and the internal and external limit gauges, fig. 11, 
are invaluable where accurate production of duplicate parts 



ENGLISH STANDARD > 
WIRE GAUGE 




Fio. 8. 



of machinery or tools are required. The value of these 
gauges are well understood in all first-class workshops, 
though they have not been used to anything like the extent 



PLATE GAUGES. 



17 



that they should be in the average works requiring to 
duplicate machine parts. The standard cylindrical gauges 
are hardened, ground, and lapped accurately to the size 
stamped upon them. 

Where work has to be made interchangeable, for success 
it is obviously necessary to lay down the limits of accuracy 




within which the work must be done. Thus, suppose the 
case of a piston rod for a steam engine as an example of this 
method of working be taken, the rod must in the cylindrical 
part be made a certain size to ensure its working, without 
heating the gland, and all the glands must be similarly bored 
within certain limits, or they will be either tight or slack on 
a rod. Now, for the glands, a gauge would be prepared like 
3wp 



IS 



MACHINES FOK SHEKT METAL WORK. 



the intemal gauge shown in fig. 11, and every gland before 
being passed into the manufactured stores would have to he- 
such a size that whilst one end would go in the other <-\i'\ 
would not enter. Thus it is obvious that the size of the hole 
must be greater than 1-249 in., and leas than 1-2M in. that 
ia, the bore is l^in. within one-thousandth of an inch. 
Closer limits, if required, might be specially arranged, 
although for all ordinary cases this limit would be amply 
sufficient. In a like manner gauges would have to be made 
for the piston rod, so that whilst one ring would slip on and 
be equally tight anywhere, the smaller ring would not go on 




Fie. lO.-Interna). 




Fio. 10. External. 

In fig. 11 the external gauge is shown with two parallel 
jaws, so that any part of the rod can be tested if either a 
tight or slack place be found when parsing the riug gauge 
along it. By making every rod and gland to gauges in 
this way, it is absolutely certain that any rod and gland that 
may chance to be found in the stores may be relied upon to 
work satisfactorily together. The whole bosineas_of_the 
engineer is to produce parts that will work together -utis- 
taetorilv, and to do this he is eniistantlv making working fits 
~of his rods and glands; but instead of determining this 
allowance once for all in the form of limit gauges, he prefers 
to do it, aa a rule, in pairs ; thus at any time there is an 



PLATE GAUGES. 

opportunity for some one or other to alter the "difference" 
allowed, and to make it either too tight or slack. 

Gauges of this type are stamped with the words " go on " 
and "not go on" for external work, "go in" and " not go ' 
in" for internal work (see fig. 11), and as the two ends are 




Fu;. 11. -Internal. 

of different shape the operator quickly learns to distinguish 
the large from the small end without referring each time to 
the legend stamped upon the gauge, after having satisfied 
himself that he has the proper one for his particular job. In 
making or using limit gauges the degree of accuracy required 
governs the variations between the two ends of the gauge 
in thousandths or fractions of a thousandth of an inch, as 
the case demands. 

The object of the metal worker is to produce a certain shaped 
article from a flat thin plate, and in consequence the material 
of the plate must be squeezed, forced, or stretched, as the 
case demands, into the given form. When the operation is 



20 MACHINES FOR SHEET 'METAL WORK. 

curried out by hand the principal tools made use of an- tin- 
hammer, some form of anvil, together with some template* 
giving the peculiar outlines called for by the design, to which 
the workman refers from time to time in the progress of his 
work. The aetion of the hammer upon the material is t 
stretch the plate locally that is, when' tin- lil..\v is given : 
there the plate is slightly thinned, and there will he in 
consequence a change of form. In the case of sheet iron or 
steel the act of hammering must be carried on upon the hot 
plate only, and if the hammering is carried on after the 
plate has cooled down below a certain limit the material will 
l>e damaged. Particularly is this the case with some 
qualities of steel. Some other metals may be worked to a 
certain point cold, but must be annealed at intervals to 
remove the brittleness produced by the hammering^ To 
facilitate this process of shaping cast-iron blocks are used, 
suitably formed, upon which the sheet is laid and gradually 
worked into its hollows by means of the hammer, fcc. But 
the operations by hand labour must of necessity be tedious, 
requiring much skill on the part of the workman, which can 
only be acquired after many years' constant efl'ort, with the 
result that the costs of production must be very heavy. 

Under the stimulus of increasing competition the aid of 
mechanical tools has been sought, initially possibly mainly 
with a view to reducing the heavy costs of assistant labour 
required by those engaged in the working of such heavy 
plates as are required in the manufacture of the steam toilers. 
The weight of these plates is very great, even in the case of 
small boilers, and the operations of flanging and shaping 
them makes it necessary to provide each workman with a 
squad of assistants to manipulate heavy hammers, and to 
move the plate from time to time into the furnace and l>ack 
again into the required position for flanging, itc. From 
uises the tools for pressing the flanges into shape, for 
punching holes, and rolls for bending are absolutely 
necessary in every well-equipped l>oiler shop to-day. 

Hut whilst in the case of heavy work the use of tools has 
taen common for some time past, the case is somewhat 

litt'ereiit in workshops where the work is of a much lighter 

inscription. The better knowledge that we JL^SL-SS of the 



METHODS OF OPERATION. 21 

lllaws of iio\v '' uf metals under pressure has shown engineers 
the_Jimitations under which materials can be successfully 

forged, infn sppf.inl ahn.pga by pressure. 

One of the earliest machines which the metal worker used 
was probably one which enabled him to stamp a pattern upon 
metal blanks at one operation, instead of slowly cutting the 
same by hand. The operation of squeezing or pressing gave 
the name to the tool which now embraces an innumerable 
number of special operations. 

The term "press," as applied to metal work, may be any* 
machine capable of altering the form of any body by squeez- 
ing, forcing, or crushing. The machine naturally takes a 
great variety of forms, and is often classified according to its 
construction and the source and nature of the power 
required for its working. For instance, the terms single- 
tsided press, double-sided press, lever press, foot press, hand" 
press, screw press, fly^press, toggle press, crank press, power 
hv'lraiilic press, Arc., and numerous other names are 
in general use. 

Then, in other cases, the name of the press depends upon 
the special operations that it is intended to perform, and of 
these shearing, punching, forming, bending, embossing, 
coining,"~^c., are familiar examples. Thus the press is 
class itl eel Tu actual practice on several lines, each of which 
has its advantages. It is the intention of the author to 
take for the first example the simplest form and the most 
commonly used of all the presses as the starting point from 
which the student and mechanic alike may study the 
development of the modern machines. 



22 MACHINES FOR SHEET METAL \\t.i:K. 



< IIAI'TKR III. 

f THE SCREW PRESS. 

V3-^ ? ' - - - . > 

THIS press is also known as the fly press, since advantage U 
taken of the kinetic energy stored in the rotating mass of 
the "fly" operating the screw. In fig. 12 is shown the 
Novation of the frame, together with a part plan and section 
of the standard. The bgse Jj is square in plan, provided 
with holes for fa stem n g do w n Th place usually on a l>ench ; 
the table or upper part is circular in plan, and is planed or 
surfacelT level, to""tate~the_bglster or boi tomjlie. When small 
work is l>eing executed, then a~^ilse~5bi torn (fig. 17) is placed 
in the recess M, which, in its turn, supports the Jx>ttom die. 
The frame is machined to accurately guide in a vertical 
direction the ram R, which is kept in its place by the strips S. 
The ram R (which is sometimes called the bolt or slide) carries 
the npper die at, its lower end, and is moved vertically by 
means of the fly F, fig. 13, which is attached to the upper 
end of the screw, fig. 14. The screw works in a nut fitted 
in the boss H, seen in the npper pait of the pre^s frame iu 
fig. 12. The dimensions of the frame will indicate the 
proportions generally adopted in a tool of this capacity. The 
screw collar, fig. 18, is screwed on the press screw, fig. 14, 
being secured by means of a set screw, the lugs A and B 
l)eing drilled for this purpose. The hole in B is tapped, 
whilst that in A is drilled slightly larger than the set screw, 
so that the collar is jammed in any required position by 
siinjilv tightening up the set screw. This collar, when in 
position, acts as a stop for the press screw by bumping upon 
the top of the boss H on the frame, tig. 12. The lower end 
of the screw, fig. 14, is reduced at I> to take the split nut 
shown in fig. 15. This nut is cut in half along a diameter, 
so that it can be placed in position ; the upper nut, which is 
large enough to pass over the collar K in the press screw, is 
then screwed in to hold it in place. In fig. 1~> the lock nut 
is shown screwed on, holding the two halves of the nut in 
position. The lower part of this nut is then screwed into 



THE SCREW PRESS. 



\ 



\ 





r \ 




P \ 




si'- 




in s " 




- -sr 




B * 




- 






: '= 


_>. 


--,-' 




'a 




= -_ 


3 





ovjo 




J4 



MACHINES FOR SHEET METAL WM|:K. 




THE SCREW PKESS. 



25 




A- 




MACHINES FOR 8HKET METAL \\UIIK. 



the upper end of the ram R, figs. 12 and 16, and the whole 
locked together by tightening the lock nut down on the ram. 






BB 



In the bottom of the hole in the top of the ram, the 
hardened steel disc BB, fig. 14, is dropped, and this takes 



THE SCREW PRESS. 



'27 



the thrust from the lower end of the screw K, which is also 
hardened. It is called the " bumping bit," and takes up the 
thrust of the blow, which might otherwise damage the screw 
thread of the split nut. The clearance allowed is clearly 
shown at T in fig. 22 ; thus the only work that has to be 
done by the screwed nut is that of lifting the ram and die 
ready for the next stroke. Connecting the screw to the ram 
is known as "gartering." 

In presses of common make this split nut is cast in 
malleable iron, which quickly wears away at W, fig. 22, but 
in first-class work these nuts are made of steel, in the 



FORCING 




PLAN AT T 



following manner, viz. : A steel forging F, fig. 23, is made both 
longer and larger in diameter than the actual finished nut. 
It is then cut through longitudinally (see D, E), after which 
the faces of each half of the forging are planed perfectly 
flat, then clamped together, and two holes e, e l are drilled. 
The halves are then riveted together, centred, turned, screw 
cut, a hexagon head milled on, and their ends reduced as 
shown at 6, b l . The nut is then screwed into a special 
chuck on a lathe. End b is now cut off, and the hole bored. 
The boring of the hole removes the end b 1 . This completes 
the operation. The split nut is now completed by hardening 
the end B, which is afterwards ground true. At fig. 1 9 is 



28 MACHINES FOR SHEET METAL WORK 

shown another method of LMI -tt-i -in.ir, in which the end of the 
screw, after being turned parallel, is grooved by a square 
parting tool, and a ring inserted. This ring is split, so that 
the two halves may be inserted into the groove. A third 
method of gartering is shown at figs. 24 and 25, which is the 




old method for the square ram. After the hole has been l>ored 
in the top of the mm, to take the end of the screw, the nun 
is slotted, to take the two halves of the garter G, after 
which two taper key-ways are planed in two opposite sides 
of the ram, [ and into these are driven taper keys, to prevent 
the garters from slipping buck out of place. A modified 




\ 



V 



SLIDE 



o 



\ 7 



.'JO MACHINES FOR SHEET METAL WOKK. 

form of tliis method of gartering is shown at fi'_ r . l'<>. \\hidi 
is to plane a broad key-way straight across the top of the 
ram, sliding the two halves into the key-way, and fastening 
them down by a set pin P. 

The ram shmvii at tig. 20 is the shape now used extent 
sivelv for the screw press, and when adopted t lie ed ires of the 
Barter are planed at an angle, to prevent any great strain 
coming upon the head of the pin P, to preveut the head 
being forced off the pin. The ends of the bumping bit, 
screw, split nut, or ring will, after being sometime in use, 
wear away. In the case of the gartering methods shown in 
figs. 19 and 22 the slack or play could be easily taken up or 
adjusted by screwing the split nut further into the bolt ; but 
in the case of gam-rimr methods shown at figs. 24, 2~>, and 
26 the slack or play would lie taken up by inserting thin 
sheet steel blanks, as shown in position underneath the 
bumping bit. 



CHAPTER IV. 

FoKM OF SCKEW-l'IiKSS FfiAMF. 

THE most common form of double-aided screw press is shown 
at fig. 27, in which the top of the frame casting terminates 
in a boss 13, which is l>ored and threaded or screw-cut to receive 
the screw attached to the ram. In large presses a better plan 
is to l>ore a parallel hole through the top of the frame casting 
(see fig. 28), and into this hole fix firmly a nut through which 
the screw can work. This nut has a collar D on one end, 
and is screwed at the other end a. It is made a tight fit 
in the frame, being forced into position. A lock nut b 
holds the main nut in position, the face of lock nut being 
screwed down upon the boss of casting C. When the press 
is being operated the strain or thrust is taken between the 
face of the l>ottom of the casting at E and the collar D. 

The single sided screw press is sh.wn at fig. 29. The 
action of the tools in a single-sided press tends to spring 



FORM OP SCREW-PRESS FRAME. 



31 



the frame by an amount varying with the character of the 
operation performed. They are usually strengthened by 
either joining K to L by an arm cast in place, or by means 





of a rod of round iron. There are, however, certain classes 
of work requiring the front of the press to be entirely 
unobstructed, and in such cases failure of the press frame 



32 MACHINES FOR SHEET MKTAL WORK. 

frequently occurs by fracturing at the point marked A, B. 
These breakages happen more frequently than many 
mechanics would imagine, even when employed upon com- 
paratively light work. Where these breakages occur a 
good method is to cast on the press a strong rib shown at R, 
which, adding very little to the weight of the press, gives 
strength where strength is required. 




Other suitable sections are shown in fig. 30, the selection 
in any given machine depending upon questions of manu- 
facture and the peculiar uses to be made of the machine. 
The student of mechanics should notice that this section is 
artu.illy strained by a bending moment and a tensile stress, 
due to the load more or less suddenly applied, according to 



FORM OF SCREW-PRESS FRAME. 



38 



the character of the operation being executed. The stresses 
produced are not exactly known, because the load is a line 
one, and a large factor of safety must necessarily be 
employed, allowing for the fact that the material is being 
repeatedly strained by a load rapidly varying from zero up 
to the maximum, and back again to zero. Under these 






circumstances the area of the section must be ample, so that 
the maximum stress imposed upon the metal may be low, 
otherwise failure at an early date is inevitable. 

Another important quality that the frame must possess 
is rigidity. If the frame should spring perceptibly, then 
there is a great risk that the dies will not meet truly, and 
this must result in broken tools. Hence in any press the 
frame should be designed on liberal lines if satisfactory work 
is wanted, for it is obvious that the cost of a few pounds of 
cast iron, suitably placed in the frame, will be a good invest- 
ment, producing, as dividend, good work, few broken tools, 
and a valuable reputation. 



4wp 



MACHINES FOR SHEET METAL WORK. 



CHAPTER IV. 
THE PRESS SCREW. 

FREQUENTLY trouble is experienced through the screw wear- 
ing badly, and it is by no means an unusual thing to find 
the screw quite slack after a few weeks' working, even in 
new machines. Doubtless in many instances this wear is 
due to rough workmanship, want of similarity between 
thread and nut, for after all the cutting accurately of 
screws with double or triple square threads is not the 
easiest task that meets the machinist. If there is any want 
of equality between either of the threads of a multiple- 
threaded screw, then it is obvious that upon one or more of 
the threads an undue amount of work must fall, with a pro- 



s s 




FIG. 31. 

portional effect upon the life of the thread. For this reason 
it is usual to mark the thread and the space in which it 
work?, so that if for any reason the screw has to l>e taken 
out of the nut it can be easily replaced in the same position 
with regard to the nut as it occupied originally. 

In the best practice, of course, the threads are accurately 
cut, both in the spindle and in the nut, so that any thread 
will work in any space with equal facility. 

The difficulties met with in obtaining a true thread may 
1*3 understood by considering the following two special cases 
illustrated in figs. 31 and 32. In the first of these is shown 
a series of parallel grooves cut in a cylindrical bar of steel 



THE TRESS SCREW. 



35 



by a square-nosed tool held stationary in the rest at right 
angles to the axis of the bar, and only moved inwards as the 
work progresses. The result is a series of grooves, the 



B 




spaces S, S 1 , S 2 , S 3 are of equal widths, and have sides 
exactly perpendicular to the axis of the bar. These grooves 




actually represent a square-threaded screw whose pitch is 



Now, turning to fig. 32, another cylindrical bar is seen, 
upon which exactly the same tool has been used, but instead 



36 MACHINES FOR SHEET METAL WORK. 

of its being held stationary, it is moved along parallel t<> the 
axis of the bar, and the liar In stationary, the result bein^r 
a longitudinal groove a of the same size and having the 
same sectional shape as the grooves in fig. 31. If the bar 
be turned through exactly 90 deg. after each groove is com- 
pleted, then there will be four grooves a, a 1 , a", a 3 equi- 
distant from each other and of equal size and similarly- 
shaped, and this may be looked upon as a square-threaded 
screw having Jour threads and of infinite pitch. 

Next, compare the shape of the projections T, T 1 , and T 2 
in fig. 31 with those in fig. 32 which are marked T, T 1 , T J . 




and T J . In fig. 31 the sides of each projection are parallel, 
but in fig. 32 they are not parallel, but a considerable angle 
is enclosed, and the reason for this difference is easily appre- 
ciated after considering the two figures. Further, it may 
l>e noticed that in order that the shape of both the projec- 
tion or external screw thread and the space or the internal 



THE PRESS SCREW. 37 

screw thread may be as nearly alike as possible, it is neces- 
sary to make the pitch as small as possible, for they can 
only be exactly the same when the pitch is zero. 

Assuming that a thread of sensible pitch is cut with a 
square tool T 4 (see fig. 33), the projection must have sides 
converging towards the axis 'of the bar (see S l , fig. 33), and 
if this operates in a space with parallel sides N 1 , then the 




pressure must inevitably fall upon the extreme edge of the 
thread, and rapid wear will occur, resulting in the appear- 
ance of slack very soon after the machine is put into regular 
operation. Sometimes a tool is used shaped as shown at T 2 , 
fig. 34, which produces threads of the shapes shown there, 




and thus overcomes the difficulty to a certain extent. 
Examples of similar threads to these may be found some- 
times in the leading screws of screw-cutting lathes. 

For these reasons it is easily seen that unless care be 
used in cutting the threads of the screw, that trouble from 
bad working and undue wear is sure to ensue. In figs. 35 
and 36 are shown examples of multiple-thread screws, that 
in fig. 35 having four threads, whilst that in fig. 36 has 
three threads. 



MACHINES FOR SHEET METAL WORK. 



S.W 




Fio. 37. 



A POWER PRESS. 



CHAPTER V. 
A POWER PRESS. 

THE press just considered is intended for use in operations 
where only a very moderate amount of energy is required to 
complete the operation to be performed, and the attention of 
the student should be turned next to a simple form of press 
intended for operation by power. In figs. 37 and 38 are 
shown different views of a press operated by means of a belt 
through gearing. The frame F, fig. 37, is of cast iron, carry- 
ing at the top the bearings, in which the steel crank shaft C S 
is placed. The brasses of the bearings are held down by caps 
C, C', which form part of the cast iron bridge piece B P. On 
one end of the shaft is fixed the spur wheel S W, which is 
driven by the jhrouded pinion S P, fixed to oue end of the 
counter-shaft C' S'. The other end of this counter-shaft 
carries two belt pullejs, one of which, L P, is loose, whilst 
the other, F P, is fixed. The ram R is moved by the 
crank through the connecting rod C R. The exact position 
of the ram is obtained by means of the adjusting screw A, 
which screws into the ram R, and is locked in position by 
the nut L N. The construction of the guide strips S are 
clearly shown in the figures, and B is base of the press, 
which is prepared to carry the lower die. On the counter- 
shaft next to the pinion is shown a cast-iron disc D, in the 
circumference of which are drilled four holes, so that the 
position of the ram may be readily moved as required 
whilst setting fresh tools in position, the belt being then 
upon the loose pulley. H L, fig. 38, is the handle operating 
the belt striking gear S G for controlling the position of the 
belt B 1 . 

In single-sided power presses the ram is frequently driven 

> by an overhung crank pin. In fig. 39 is shown an example 
of this form of construction. The ram is slotted S at the 
back, and in this a block N is fitted, so that it can move 
freely from side to side of ram. The block is bored to suit 
the crank pin (see fig. 40). The guide strips are shown at 
S 2 , S 1 in the plan view, fig. 39. 



40 MACHINES FOR SHEET METAL WORK. 



B 




A POWER 1'KESS. 



41 



' Fig. 40 shows the complete arrangement The driving 
shaft C S has a pin let into its enlarged end to form the 
driving crank, the construction being clearly shown- in the 




left-hand sectional view. The right-hand drawing shows 
the front view, one of the guide strips and the ram having 
been removed so that the block N is shown in its position on 



42 



MACHINES FOR SHEET METAL WORK. 



the crank pin, and the lower view shows the relative 
positions of the various parts. 

Another method is illustrated in fig. 41, and it will be 
noticed that the slot extends completely through the ram ; 
in fact, it is a rectangular hole. The depth of the slot is, 



B' 




however, greater than necessary to accommodate the block 
X, in order to accommodate the thickness strips shown, 
which are used in order to provide a means of adjusting the 
relative positions of crank pin and bottom of the ram to 
suit different sets of tools. This adjustment is obtained by 
varying the numter above or below the block N, according 




FlO. 42. 

to requirements. The six strips, a to a 8 , are all different 
thicknesses, to enable minute adjustments to be made, and 
are shown to a larger scale in fig. 42. They are retained in 
their proper position by means of a metal sliding cover held 
in place by the beveled edges shown at P', in fig. 41. Crank 
pin, fig. 41, is turned solid on the shaft. 

The method of driving the ram shown in fig. 39 is open 
to objection, because of the^sfipst'^ ynr thnt often ocmira 



in_the_8J2t_S which leads, of course, to noise due to back- 



A POWER PRESS. 43 

lash. This hammering in its turn increases the damage done 
both to the slot S and the block N, sometimes in the case 
of the design shown at fig, 40 causing the crank pin to work 
loose. The tool-setter, in taking up the slack by the packing 
strips S x So, can put a heavy load upon the machine, thus 
reducing its effective capacity, straining the crank pin, and 
grooving of the sides of the ram. To prevent this [the 
] machine fitter, when fitting in the strips Sj S.,, should makft. 
them butt on the machine casting, metal on metal. Then, 
should grooving take place, it can be traced to imperfect 




C.P 



adjustment of the side screws for setting up the strips Sj S 2 . 
Where this design is employed, the crank pin should be 
made of large diameter, and as short as possible, in order to 
obtain stiffness. In many Instances, alter a crank pin has 
given trouBIe" by bending, cutting oft' one-third of its length 
has removed the difficulty. 

The power press is sometimes driven by means of a_clutch 
instead of using fast and loose pulleys as shown in fig. 37. 
One form of clutch is shown in fig. 43. The wheel W is a 



tl 



MACHINES FOR SHEET METAL WORK. 



tlywheel pulley fitted with a brass Imsh and running freely 
on the shaft. The boss is continued so as to form the jaws 
of the clutch, as shoan at WC, a perspective view beinir 
slmwn in tig. 44. On the end of the shaft the other half of 
clutch (J is fitted so that it may slide freely along the axis of 




CLUTCH WC 



CLUTCH C 




the shaft, but it cannot rotate upon the shaft, the two keys 
K being fitted for driving the shaft This part of the 
clutch C is moved to and fro by a lever and rollers operating 
in the usual manner, the groove being provided for this 




Flo. 4'j. 

purpose. The mode of action is easily understood by 
reference to fig. 44, which shows the relative positions of C 
and \V C when the clutch is engaged. This clutch was 
intended for intermittent working, and i* only suitable when 
the press is running continuously for long periods without 



A. POWER PRESS. 45 

being stopped. It is obvious that the shock at starting is 
only tolerable when the speed is low, and in consequence 
this form of clutch is very liable to damage, but in certain 
classes of press work it can be used with advantage. Any 
damage to the clutch is a serious matter, for castings cannot 
always be easily replaced, so that the jaws may have to be 
put into working order by means of hand labour, always a 
costly business. 

In another form of clutch, fig. 45, a wrought-iron or steel 
pin V is fitted to the sliding collar 0, and passes through 
the boss of the flywheel pulley F W P, engaging with the pin 
L, which is fixed into the collar M, which is keyed fast to 
the shaft. In the position shown in the figure the clutch is 
disengaged, the pin V, as it rotates with the clutch and 
flywheel, passing clear of the pin L, and the coupling is 
effected bv sliding to the left when the pin V engages with 
the fixed pin L. This form of clutch is open to the same 
objections as the preceding, but has the advantage that the 
pins V and L can be more easily replaced in case of damage, 
since it can be made from a wrought-iron bar of suitable 
diameter very quickly. 



CHAPTER VI. 

FAULTY CONSTRUCTION. 

THE press shown in fig. 46 has been selected by the author 
as an example of poor design, and the results obtained in 
actual operation practically justify the statement that they 
are complete failures. The press is belt driven ; a flywheel 
F W is fitted to the pulley shaft, arid the crank shaft is 
driven by means of the pinion P and spur wheel S W, the 
ratio of the gear reducing the speed of the pulley shaft 
down to 25 revolutions per minute at the crank shaft. 
Four rams may be operated simultaneously, or by means of 
the clutch D ; the two presses on the right may be discon- 
nected. The press is one of great power, the crank shaft 
having a diameter of 6 in., the stroke of the rams being 



46 MACHINES FOR SHEET METAL WORK. 

I. 1 , in., and the ratio of the gears 5 to 1. At the extreme 
nirht will be seen a pair of shears L, driven by means of a 
connecting rod (not shown) from the end E of the crank 
shaft 

The reason for adopting this design of press was economy 
of first cost, as compared with the outlay necessary to secure 
four independent presses. This leads at once to one great 
disadvantage of the design i.e., impossibility of independent 
operation of the several presses. It is impossible to operate 
the two right-hand presses without running the other two 
at the same time, and it is not necessary to remind the 
practical mechanic that it is very difficult, if not quite im- 
possible, to secure the conditions that will allow of all four 
presses remaining continuously at work. Each time that 
either of the presses have to be stopped, the remainder 
must also stand ; thus the total time wasted will be at le<st 
four times that which would occur had some independent 
system of driving been adopted in the design. To secure 
this independence would not have involved any serious out- 
lay when the value of continuous working is allowed for. 
It could have been secured by any of the familiar devices 
used in punching and shearing presses that are belt driven 
and run continuously during working hours. 

An examination of the construction of the frame will 
reveal the multiplicity of joints between the floor and the 
crank shaft, each of which increases the chance of something 
working loose, or irregular settlement, and so forcing the 
shaft out of correct alignment. In the design (fig. 46) it 
will l>e noted that a brick pier supports one end of the pulley 
shaft, whilst the outer bearing is carried on a cast iron 
pedestal resting on a wooden block, which may shrink, etc., 
whilst the presses are fixed to a wrought-iron angle iron 
resting upon the brick pier at the extreme left end, and four 
cast-iron pedestals, supported as before upon a wooden block. 
If the various ways in which this frame can give trouble are 
counted up, considering lxth errors of workmanship in con- 
struction and erection, as well as carelessness in supervision 
during its operation, the advantage of a perfectly solid and 
rigid frame as free as possible from joints will be fully 
realised. 



A POWER PRESS. 



47 



r 




MACHINES KOR SHEET METAL WORK. 

The end view, fig. 47, together with fig. 46, will show the 
construction and method of erection very clearly, and will 
not require any further explanation. 




In order that eitluT of the four presses may be stopped for 
tool setting, &c., the mechanism shown in fig. 48 was devised. 



DIRECTION OF ROTATION. 49 

The shaft is rotating continuously in the direction shown by 
the arrow, and the lower part of the eccentric strap is shaped 
so that there is a solid mass M to receive the stress due to 
the thrust exerted upon the ram on the down or working 
stroke, and a projection P which engages in a recess E formed 
on the upper part of the ram ; by this means the ram is 
lifted for a second stroke. The heavy balance weight W is 
to prevent any possibility of M being forced out of gear 
when the load comes on, whilst the handle H is provided 




for lifting it out of gear when the press has to be stopped, 
a suitable catch being fitted to hold the handle out of gear 
until the press is ready to commence running again. 

An important matter in press construction is to arrange 
the direction of rotation of the shaft so that the load due to 
the reaction at its point of connection to the ram, due to 
ifcs obliquity, shall come on the frame of the press con- 
tinuously. The diagram in fig. 49 will make this clear. 
In the tig. is the centre of rotation, and C the centre of 
the crank pin rotating about in the direction shown by 
the arrow. The ram K is being raised between the frame F 
5wp 



50 MACHINES FOR SHEET METAL WORK. 

of the press and the cover plate P, and obviously the con- 
necting rod K must l>e in tension, since a chain might replace 
the rod and the ram lifted. But this pull in the rod K is 
exerted against the weight of 11, which is acting downwards 
in the direction of a line drawn vertically through the centre 
of gravity of the ram. Thus there are two forces acting 
at the point of attachment A of the connecting rod K and 
the ram R, one k upwards in the direction of K, and 
the other W vertically downwards, as indicated in fig. 50. 
Under the action of these two forces the tendency of A is to 
set itself in the line joining the centre of the crank pin C 
and the centre of gravity of K ; but since the face of the 
frame F prevents this movement, there must be a pressure 
exerted agoinst F. The amount of this pressure can be 
ascertained readily by making the length A W, in fig. 51, to 
represent the magnitude of the weight W of the ram to 
some convenient scale ; then through A draw a line A Q 
parallel to the direction of the connecting rod K, and, finally, 
through W draw W X at right angles to A W, meeting A Q 
at F ; then 

the pressure on the face (F) _ F W . 

weight of the ram A \\ 

and 

the tension or pull in the connecting rod (k) _ AF 
weight of the ram A \V 

Since the angle between the centre line of the connecting 
rod and the vertical is continuously varying during the stroke 
from through some maximum value back to zero again, it 
is obvious that the line A Q will swing from A W to some 
position A Q and back again to A W, so that the length of 
the intercept W F will vary from when the ram is at the 
bottom of its stroke and the crank at GI, to a maximum value 
W F when the crank is at C, when the angle C A is 90 deg., 
back to zero when the ram is at the top of its stroke t.f., 
when the crank has reached the point C,. 

By similar reasoning it will be seen that on the down 
stroke that is, whilst the crank is moving from C 2 to C and 
thence to (,\ the crank is pushing the ram down, the stress 



THE RELATIVE POSITION' OF CRANKS. 



51 



iu the connecting rod is changed from tension to compression, 
and the resistance due to act of cutting or stamping, the 
ram's motion downwards is resisted that is, at A we have, 
as before, two forces acting again, but their directions are 
reversed, and are shown in fig. 52. The result of these two 
thrusts at A is to cause a movement of A to the left, which, 
as before, is resisted by the frame F. The magnitudes of 
these forces can be found as before, the exception being that 
the line A "NV must be of such a length as to represent the 
resistance offered to the die by the material being operated 
upon, less the weight of the ram, die, etc., which, of course, 
assists the press to do its work. The direction of rotation 



V 



7 



W 

FIG. 52. 



should be so arranged that the pressure should always conic 
on the machine frame, and not upon the cover holding the 
ram in place. This is a small point, but an important one, 
to be considered, for the smaller the strain that comes upon 
the bolts securing the cover can be made, so much are the 
risks reduced of having difficulties with loose cover plates, etc. 
Another point that must be paid attention to in multiple 
presses such as that shown in fig. 46 is the sequence of 
the cranks, or ti-ouble will be experienced in the regular 
working of the machine. The action of a press is inter- 
mittent that is, during a very small portion only of a 
revolution the whole of the work has to be done, and thus 
for a short period the pressure exerted is very great. The 



52 MACHINES FOli SHEET METAL WORK. 

object of the flywheel is to store up energy during the idle 
period of a revolution of the crank, in order to overcome the 
resistance ottered to the movement of the die without 
throwing off the belt. In the case of a multiple press the 
cranks must therefore be spaced at intervals of equal angles, 
so that the working loads come regularly. In the machine 
shown in fig. 46 there are four presses ; hence during a 
single revolution of the crank shaft there are four working 
strokes, and the cranks are spaced at angles of 90 deg. to 
each other. But in this machine, since the coupling I) 
allows two presses to be disconnected, it may so happen that 
only two presses may be at work, and to meet this each of 
the two crank shafts have their cranks at 180 deg., or 
opposite to each other, and when they are coupled the 
second shaft is set with its cranks at right angles to the first 
shaft. Thus, if the presses be called No. 1, No. 2, No. 3, 
and No. 4, counting from left to right, then the sequence of 
events are shown by the following table : 



Press cutting. 



When crank No. Us 



No. 1. on its buttom centre. 

No. 3. has moved 90 deg. from its bottom centre. 

No. 2. -has moved 180 deg. from its bottom centre. 

No. 4. has moved 270 dejr. from its bottom centre. 

Or if the presses Nos. 3 and 4 are disconnected, then the 
sequence is 

Press cutting. When ciank No. 1 is 



on its bottom centre. 

has moved 180 deg. from its bottom ceutic. 



lu tliis way uniformity of speed is obtained. The flywheel, 
however, must be designed so as to meet the worst case 
t'.f., the conditions of working when the idle period is (east; 
and will lie dealt with presently. 



DIES AND I'UNCHIS. 53 



CHAPTER VI F. 

DIES AND PUNCHES. 

DIES and punches are of infinite variety and shape, special 
forms being devised daily by engineers in order to produce 
some new shape that may have to be manufactured. It 
would be absolutely useless to attempt anything here in the 
way of a complete exposition of the subject, and only the 
most commonly used forms will be dealt with, pointing out 
the leading features of the design, so that some idea of the 
conditions that have to be fulfilled will be brought before 
the notice of the reader. 

The._die is the lower tool that is fixed to the bed of the 
press, and has a hole pierced through it, so that the blanks 
forced out by the punch can fall away ; or it may be 
hollowed out to suit the shape required, where the work to 
be done is pressing, or stamping some special shape from 
sheet metal ; or there may be combination of form, with 
one or more holes to be punched. 

It will be obvious, therefore, at the outset that the die 
will have to sustain a very heavy load, during the time 
the operation is being carried out, without suffering an 
dejtprmation. In man}* instances the blanks formed,j 
holes punched, have to be true within very small limits, and 
the dies must not need continuous i-xainination to discover 
where the wear, &c., is such that the work produced will be 
rejected, but should retain its efficiency for a long time. 




In order to retain its shape the effective portion 
must be made of the best steel, suitably hardened to meet 
tile special requirements of the operation to be executed ; 
and to meet the great strains imposed, its mass must be 
very_large. But since the cost of suitable steel is much 
greater than that of iron, it is the practice frequently Jtojit 
the _steel die proper into a suitable block of wrought iron. 
The weight of the iron put into the block must be pro- 
portioned to the severity of the strains that may be expected 
in actual work, and for which no mathematical rules are 



54 MACHlNtS FOR SHEtT METAL WOKK. 

easily applicable, the designer's experience alone l)eing 
usually depended upon. There is a certain si/e at which 
the cost of building up the cum] mi'! ilie \\ill cM-i-cil the 

saving effected by using iron Tu the^ place of steel, In 

piim-hing pivss,-<. tor example, for ordinary sizes there is 
not any advantage gained by making the outer part of the 
die of iron. In some cases the cast-iron frame of the 
machine itself is quite sufficient, because its mass ma}' l>e 
easily made comparatively very great. 




The process usually followed in the manufacture of a 
compound die is illustrated in fig. 53, the first stage being 
the formation by the smith of a hollow in the wrought-iron 
bed ; next, a piece of steel is inserted and the iron closed as 
tightly upon it as possible. The third stage shows the block 
with the iron and steel firmly welded together. The hollow 
in the steel centre is formed by the tool smith to reduce the 




work of the tool maker when shaping the die accurately to 
the specified dimensions and contour, as shown in the fourth 
stage. Fig. 54 shows three other different shapes of stamp 
dies. The dotted line indicates the depth of metal left by 
the tool smith for machining purposes in the tool room ; 
whilst fig. ."> illustrates a drawing die in which the steel 
centre has a wrought-iron ring surrounding it, the hole 
in the steel centre being afterwards bored out accurately 
by the tool maker, where the work to be done is that of 



THE FORMATION OF DJES. 



55 



cutting out blanks to some special shape ; then the steel is 
worked into the iron bed by the smith, the face and hole 
being shaped by the tool maker, so that the upper edge of 
the hole in the steel centre forms with the punch a pair of 
cutting edges. Fig. 56 shows two methods of making beds 
intended for cutting out long round-ended blanks. The bed 
A has an iron bottom and steel top, which, after being 
forged, is machined nearly all over ; whereas, in the case of 
B, the bed is cut off a solid bar of steel by the tool maker 




and machined, thus avoiding the cost of forging. The hole 
to receive the punch is clearly shown in fig. B. The holes 
should increase slightly, so that there is sufficient clearance 
for the blanks to fall freely immediately they are formed, or 
otherwise difficulties may arise. 

Where possible the correctness of the die is tested before 
hardening, but this cannot always be done, because the 
material will be unable to withstand the stress in its un- 
hardened state. When the dies are correct they are hardened 
and tempered to_a light straw colour. Thi& process of 
h'arcToning and tempering dies so that thev are able to 



66 



MACHINES FOR SHEET METAL WORK. 



successfully withstand the rough usage of the press is one 
of great importance, depending ultimately upon the care 
exercised by the tool maker entrusted with the work. The 
great point apparently is to heat the articles to l>e hardened 
as uniformly as possible to the required temperature, nnd 
then to cool them more or less quickly and evenly, so that 






the internal stresses shall be as equal as possible. Cracks 
result from failure of the material, due to the excessive 
internal stress ; whilst fracture soon after work is com- 
menced indicates that the stress due to the external load 
sufficed, when added to the internal stresses already existing, 
to strain the material beyond its "yield point,'' and failure 
results. At other times failure only occurs after many 
applications of the load, the "fatigue" reducing the ultimate 



11AKDEM>0 DIES. 5? 

strength more or less quickly according to the magnitude of 
the internal stresses in the material due to the hardening 
and tempering processes. 

The practice of the careless smith is to put the tool to be 
hardened into the fire, so that whilst one portion is rapidly 
warmed up another part is out of the fire and almost cold. 
The tool is presently turned over to warm up the colder 
part, when the heated side is cooled down ; finally the tool 
is rapidly twisted about, so that as far as the eye can judge 
it is properly heated. If a fire is used, then the tool should 
])e actually covered entirely over, and the process of heating 
up carried out slowly and evenly throughout the whole 
mass, so that the temperature is even throughout. Probably 
the best way to ensure this regular heating is to use a gas- 
fired furnace or muffle, which can easily be arranged to 
maintain the correct temperature by adjusting the gas 
supply, and in this way there is no risk of burning the steel 
if the workman should be unable to remove it when ready 
for cooling. Another incidental advantage of the gas-fired 
furnace is its economy in working both as regards cost for 
labour in handling the fuel and the increased cleanliness due 
to the freedom from smoke and dust, which are inseparable 
where the ordinary smiths' fires are used. 

The dies should be left as soft as the natura of the work 
will permit as the internal stresses are proportionately 
reduced, leaving a wider margin of safety in actual work, 
and a proportionately longer life, before repairs or renewals 
are required in order to preserve the necessary accuracy of 
form. 

For the manufacture of dies and punches a__careful_ 
aejection_pf the steel employedjs of the utmost importance, 
for if the quality of the steel employed is not suitable, it 
will be impossible to make satisfactory tools, notwithstanding 
the utmost care exercised by all concerned during their 
production. The amount of hardening possible depends 
xxpon the quantity of carbon present, and for the purpose of 
tools that will stand a great pressure, as in the case of dies, 
<tc., the best proportion of carl ion is nbnnt par cerrL. 
Increasmg the amount of carbon to - per cerffc giyes_ an 
exceedingly tough steel suitable for "cold sets," and similar 



58 MACHINES Full SHEET MtTAL WORK. 

tools that have to withstand very heavy blows. For chisels 
and similar tools, where ability to withstand heavy usage, 
and yet to harden sufficiently to give a cutting edge, the 
steel should contain about 1 per cent of carl>on. Increasing 
the amount of carbon beyond 1 per cent yields steels having 
greater hardening powers, and consequently increasingly 
brittle, whilst the metal requires much more care to work 
satisfactorily. 




F 
Fio. 57. 

The upper die used in stamping out work is shaped to suit 
the inner form of the article to be produced, and is usually 
termed" the force." It is made of various materiaTs71b~iuTT 
uM special conditions to be satisfied. Tin, brass, iron, and 
hteol are the materials most commonly used. The force is 
held in the stamp hammer in several ways. Fig. 57 shows 
the face of the hammer notched or grooved, into which 
the force is pressed. In fig. 58 Ihe force 



MAKING STAMP FORCE. 



59- 



groove, whilst in figs. 59 and 60 it is securedby_jnfiaiis of a 
screw~S pressing on to the spindle as in an orcunary drilling" 
machine. 

The operation of making a tin force is illustrated in figs. 
61 and 62. In the first of these C is the d^j_^wujcUferiaed_ 
round the top of the tool, into which the molten tin T has 




been poured, thus forming a casting for the force. The 
head of the hammer K the face being ready notched .is 
then carefully lowered, the tin filling the interstices in the 

fa co of K, and securing the force accurately in place. 

The brass force is made by using a tin force as a pattern 
to make a mould from in the foundry as in the ordinary 
course. 



60 MACHINES FOR SHEET METAL WORK. 

Iron and steel forces are formed first by forcing the 
hammer face K into the rough force F, fig. 63, the iron l)eing 
heated for this purpose. When this has been done the force 
is again re-heated, and repeatedly forced into the tool 
until it has been squeezed into the exact form. Where the 
shape of the force has been much upset by the process of 





Fio. 



forming the "jag," time may be saved in the last operation 
if some of the metal at a, b, fig. 64, be roughly turned off. 
This is always true when the die is a deep one. The turning 
operations are facilitated by the use of a template. Care 
should be taken in these operations not to let the force get 
cold whilst it is being formed, or the lower die will be 



PUNCHING AND SHEARING. 



1 



damaged. In fig. 65 the bar of iron B is placed above the 
die to protect it whilst the force is having the jag formed in 
its upper face. 






FIG. 63. FIG. 64. 

PUNCHING AND SHEARING. 

The term punching is generally understood to include all 
ojjeraioJia_Df_cutting out blanks from sheet metal. The 
shape cut away is known as the Hank, whilst the 
unavoidable amount of metal sheet left afterwai'ds is only fit 



iff 



C2 



M.VHIXES FOR SHEET METAL \\<>KK. 



for scrap. Some ingenuity is required to so arrange the 
sequence of successive puuchings that the amount of scrap 
shall be a minimum. 

SJi>nrin'i is tin- >|.'.T:it i<n ..f cuttiiiLT n]> >ln-.-r ii,,-t:il. il.r 
bars, &c. t iuto lengths, strips, <fcc. The action of a punch is 
tKaTTof shearing, and a punch may be_j:egarded a | ja 
endless shearing tpoIT 

~The load that comes upon a punch is wholly compressive, 
and very heavy. The limiting thickness of metal that can 
be punched without haatinft fly pimph ] being dependent 
upon the relative resistances of the die to compression, and 
of the plate to shearing. 





Let/',. = crushing stress in pounds per square inch of punch; 
d ^ diameter of the punch in inches ; 
D = diameter of the hole punched in the plate in inches ; 
/, = shearing stress in pounds per square inch at which 

the plate yields /to the punch ; 
t = thickness of plate in inches. 
Then at the instant of rupture 

The load on the punch = maximum resistance offered by 
the plate to punching 



THICKNESS OF PLATE THAT MAY BE PUNCHED. 



63 



if the difference between d and D is so small that it may be 
neglected, then putting d = D we have 



Taking the case of best Yorkshire iron plates, then /, is, 
according to Professor Goodman, about 19 tons as the upper 
limit, and for tempered cast steel f c may be taken at about 
85 tons, the exact figure, however, depends upon the amount 
of hardening and the quality of the steel, then using these 
values the ratio 



d 4 x 



19 = 76 = 0-894. 



t 85 

That is, the theoretical limit of thickness is, in this case, equal 
to the diameter x by 1 '118, which agrees with the practical 
rule_which puts the maximum thickness as being equal to 
the diameter of the hole punched.,. The limiting diameter of 
;my hole in a plate t inches thick of any material is 

_ t x 4 x the limiting shearing stress 
safe working crushing stress of punch' 

In this connection the following figures will be useful in 
connection with the above formula. 



Metal. 


W. iron. 


Stesl plates. 


Copper rolled. 


Brass. 




1 40 000 


1 50,000 I 




.... 


Crushing 


..! to.oco 


( 83,000 


| 
28,000 


( 20,000) 
( izu.'ouu ) 



From experiments that have been made, it is found that 
the area surrounding the hole in punched boiler plates is 
injured by the severe stresses caused by the pressure of the 
die, and the extent of this injury is given by Professor 



Goodman as about 



y 



an inch deep round the hole. 

For this reason, whenTplates have bee a punched or cut by 
shears it is customary to plane the edges of such plates and 



MACHINES Foil SHEET METAL \\O11K. 



ream out_jthe punched boles. The pressure on the plates 
"makes them brittle, and if the plates be tent, cracks drvt'l-ip 
iu the crushed parts. 




To reduce the magnitude of the total load, it is common 
practice to give a slope to one of the cutters in a shearing 
machine, as shown in fig. 66, the amount of this clip BeTng 






Fio. 67. 



from 5 deg. to 15deg. This dip has also the effect of 
extending the time (luring \vhidi thr cutting is going on 
over a longer ' jnjtervtxT,_ \vith__ tin- ivsuH of reducing the 



CUTTING ANGLE ON PUNCH. 



stresses generally on the machine. The_ angle of the cutting 
edges, "and the position of the plate to be opefated^upon7i3 
shown clearly in the figure. 

The details of punching tools, it may be noted first 
that whilst cutting-out punches are given shear for the 
purpose first referred to in shearing cutters, yet generally 
the ends of the punches are faced off flat that is, at right 






angles to the line of motion, thus there is no shear, and the 
cutting angle is 90 deg. An example is shown in 
fig. 67, where the cutting edge D is equal to 90 deg., whilst in 
fig. 68 is a similar punch, but the central part of the face is 
cut away, making the cutting edge D less than 90 deg. 
Tliis is of some advantage when the punch becomes worn, 
anH.jequireH upsetting^ tojmable the original diameter tojbe 
regained. 

For tools that are to cut blanks from thin sheets of brass 
and tin, particularly those of large area, it is usual to harden 
and temper the lower die to a straw colour, and leave the 



CO MACHINES FOR SHEET METAL WORK. 

punch company tivelyjjoftj i.t., it would be hardened f but_ lgt_ 

<l\vn in tempering to a nine colour. \Vlh-n su<-li :i punch li.-ts 
worn, the punch can be~Tiamrnered up around its cutting 
edge, and then forced into its own die, to bring it np to 
correct size again. This is necessary when the metal sheet 
is thiii, say less than 7 7. 7 in., then the cutting tools to do 
ff>od \vrk require to be a good" fit, butj with thicker sheets 
therejnnst be some clearance varying from T g ^ i n^ to about 

. The 



in., according to the nature of the work. The result ot" 
any "freedom when working on thin plates is to leave_a 
ragged ed^e or fraze on the blanks. 

Tf the blanks have to be cut from steel plfttes, the punch 

Millet In- li;ir.lrll'-<l illl'l teillpeiv 1 tin 1 viliie :i* tin- 'lie if 

{uniformity ~Qf size is necessary. but this hardened puncTi 
must have some freedom in the lower die, or the friction 
will increase the rate of wear, and entail extra work upon 
the tool-maker in grinding, etc. The amount of 

~~~ 



a_ni-e required depemls upon the size~~~or~tTiV P^Hg^ tH_e 

k to be 



thickness of the plate, and the nature of the work 
done; in some cases , ,' MJ -in. will be suttirient. whereas, if it 
is boiler plate, or gir<TeT work, the clearance may.be as much 
j{g~ji ff in. The effect of clearance upon the size of the blanks 
iTToTrender them taper, their top side will be the same 
diameter as the punch, and the lower face will correspond 
to the diameter of the hole in the die. 

Punches may be made solid, in which case they require 
some forging, or they may be made up in the tool room 
without the aid of the smith. Each plan has its advan- 
tages, the built-up tool requiring to be well made or it will 
lack rigidity, and fail to do good work in consequence. In 
punches of small diameter they are drawn down from a larger 
bar of tool steel, the upper end of a suitable size to fit the 
ram ; the lower end the diameter of the hole or blank 
required. Sometimes the punch is left perfectly parallel, 
but in many cases there is a slight taper which may tend to 
slightly increase the diameter of the punch as iLJitcars.back, 
/ or may reduce its diameter. 

It is sometimes convenient to build up a punch of large 
diameter for cutting out blanks, and one such composite 
punch is shown in figs. 69 and 70. In this example the 



PUNCH BUILT UP IN SECTIONS. 



67 



tool consists of three parts, the cutting part F formed of 
hardened steel, attached to the part B (which may be a 
casting) by means of three or more small screws. The 
shank S is parallel and enters the ram, whilst H enters 
the casting B. This tool can be made without the aid of 
a toolsmith, and several different sizes of cutter F can be 
made to suit B, the hole in F being machined, so as to fit 



. 




exactly concentrically without the assistance of the screws. 
The casting B may be attached to the shank H by heating 
and shrinking in the usual way. 

A very common method of fixing punches to the ram is 
shown in fig. 71, where the shank is screwed into the ram, 
flats being provided so that it may be tightened by means 



88 



MACHINES FOR SHEET METAL WORK. 



of a spanner. A better method of fixing is shown in fig. 72, 
where the shank of the punch is turned parallel and made 






to fit the hole in the ram, and secured in its place by means 
of a set-screw. This is necessary in order to prevent its 



METHODS OF FIXING PUNCH. 



being pulled out on the up stroke of the ram, when con- 
siderable force is often required to withdraw the punch from 
the hole it has made. 

A_badly^fixed punch means bud work and many broken 
tools, because when the pressure comes upon the tool it will 
'"Hack" or spring aside, if it does not press evenly upon the 
material from which the blanks are being formed. The load 
that comes upon the punch is very great even when but 
small holes are being punched, and when this is fully realised 
the necessity for good workmanship will be readily admitted. 

.__jiiLdexs<wi-' gives some interesting figures obtained by 
means of a series of careful experiments in which the load 
upon the punch was gradually increased until the hole was 
punched. 



Diameter of 
punch. 


Thickness of ; Sectional area 
plate. of plate. 


Total load on 
punch. 


Stress per 
square inch. 


Inch. 


Inch. Square inches. 


Tons. 


Tons, i ' 


1 


0-437 0-314 


8-384 


24'4 " 


J 0-025 0-982 


26-678 


27-2 /" 


1 


0-625 


1-472 


34-768 


23-6 


3 


0-875 


2405 


55-000 


23-1 


i 


1-000 


3-142 


77-170 


24-0 




In the Transactions of the Institution of Mechanical 
Engineers of 1858, particulars are given of some experi- 
ments made with punching presses, from which we take the 
following results : 



Diameter of 
punch. 


Thickness of 
plate. 


Sectional area 
of plate. 


Total load on 
punch. 


Stress per 
square inch. 


Inches. Inches. 


Square inches. 


Tons. Tons. 


1 


0-5 


1-571 


36 22-00 


1 


1-0 


3-142 


69 21-95 


2 


0-5 


3-142 


65 20 70 


2 


ro 


6-2S3 132 21-00 


2 


1-5 


9-425 


186 1973 



70 



MACHINES FOR SHEET METAL WORK. 









Mr. Hick^of Bolton, found the load required to force a 
punclTBin. diameter through a plate 3iin. thick was 2,000 
tons, or 22'74 tons per square inch of area. 

The load upon the punch can be estimated ronffhlv by 
multiplying tti-x'tlu-r the diameter of the punch, the thickness 
of the plateT^TRe slr'eslTper "square inch of area, and 3;1 f. 
Stated algebraically, if D" =" diameter of punch in inches, 
t = the thickness of plnte in inches, / = the resistance 
offered by metal in tons per square in., and the load upon the 
punch in tons = L, then 

L = d x t x / x 3-14. 

The figures given above show that the total load upon 
the punch is very great, and unless it is properly secured the 
tool must be very severely strained. These figures also show 
that the load upon a punch is approximately equal to the 
tensile strength of a bar, the area of whose cross-section 
is the same as the area of the sides of the hole. Thia plates 
appeared in many instances to require a greater load than 
was necessary in the case of thick plates, and the reason for 
this probably will be found due to the skin effect of the 
hard exterior surface of rolled plates. 

It must be remembered that the operation of punching 
and shearing is not strictly cutting, but rather a detruding 
action. The time occupied in punching is due to the 
elasticity of the material, the punch, and the parts of the 
press. When this elasticity and slackness are all taken 
up, then the resistance of the material is at once overcome, 
and the metal is detruded, or pushed off, rather than cut 
away. After the operation is completed the resilience of 
the machine in assuming its normal condition gives rise t' 
thVwell-known jerk or knock which ig^ heard immediately 
the blank is detached. 

~~The~behaviour of materials under pressure has been the 
subject of many experiments, and the plasjjc properties of 
solids are now fairlv well known. If a solid sulistunce l>e 
subjected to a stress gradually^ increased, careful observation 
will show that at first there is a period of nearly perfect 
elasticity, when the variations of length are exactly propor- 
tional to the stress, and if the stress be removed the body 



ACTION OF PUNCHING AND SHEARING. 



71 



returns to its original length, If, however, the load applied 
be increased still further, then a second period is reached 
when the alteration of length is no longer proportional but 
rapidly increases with the augmented loads. If the lond be 
removed after this second stage is reached the body will not 
regain its original length, but will remain permanently 
stretched. If this second period of deformation be further 
considered, it will be seen that it tends towards that 
condition in which a force sufficiently great would go on 
stretching the material, as occurs in the operation of 
drawing lead wire. This particular condition M. Tresca first 
called the period of fluidity. In certain materials, such as 
glass, this period practically disappears, but in the case of 




/ *' 

7~e- / , 




malleable metals it is very much extended. M. Tresca 
found from his experiments that large plnstic deformation 
is not associated s'ith^anv sensible chang_e oCjJeusity. The 
following examples will serve to illustrate the flow of metal 
that takes place iiuder the action of the punch, and are 
taken from the results of the experiments already referred 
to. Suppose a block to be supported on the die of a 
machine, and to be perforated by a } unch. If the blank 
produced is carefully measured and compnred with the 
thickness of the block, in general it will be found to be less, 
that is, h is less than H (see fig. 73). In one case H was 
10 centimetres, the hole punched was 2 centimetres diameter, 
and the thickness of the blank was only 3 centimetres. 
The density of the blank was determined precisely, and 
found to be the same as that of the original block, con- 



72 



MACHINES FOR SHEET METAL WORK. 



sequently during the act of punching 70 per cent of the 
metal must have floived laterally into the block. 

In another case where the punching was only partially 
performed, as shown ia fig. 74, the thickness of the blank was 
easily seen to be less than the penetration of the punch 
without having recourse to measurement. A further 
experiment may be mentioned, in which a series of lead discs 
were placed upon each other and then punched. After 
l>eing cut in two the appearance of the block and blank 
produced was as shown in fig. 75. The blank consists of 
an equal number of discs, but their thickness has been 
changed, and it will be seen from the figure that the depth 
of each disc difiers, the thickness of each gradually increasing 




FIG. 74. 



FIO. 7:.. 



from the top to the bottom of the blank. Of the metal forced 
to flow laterally the greater part has been obtained from the 
upper discs. From these experiments the student will 
easily infer that under the pressure of the punch, the metal 
becomes plastic and flows, till the remaining metal is so 
thinned that its resistance to shearing is less than the load 
on the punch. Further details upon the " Flow of Solids " 
can be found in the Proceedings of the Institution of 
Mechanical Engineers of 1876 and 1878 ; and also in an 
article on "Elasticity" in the " Encyloptedia Brittanica" by 
Lord Kelvin. 

Obviously the best way to fix the punch is that shown in 
fig. 72, because the whole load comes upon the shoulder which 
can be turned true, and thus there cannot l>e any tendency 
to force the punch out of line. Probably the reason that 



PARALLEL AND SCREWED SHANK COMPARED 73 

screwed punches have been so much used in the past is due 
to the facility with which a punch can be secured tightly 
into the ram, by means of a spanner, as contrasted with the 
trouble given by a punch with a shank that is not parallel, 
although it may be called so. 

Parallel punches may be made from round bar without 
the aid of the smith, and if suitable jigs and gauges are 
available may be completed ready for use without the tool 
maker going near any of the presses in which they will be 
used. 

In order to prevent the punch from being drawn out of 
the ram on the up-stroke, a flat or hole should be provided 
for the set screw to bed against, and so hold the punch 
firmly. This precaution is very necessary in the case of 
large cutting-out tools, also in cupping and drawing presses, 
in each of which operations there is often a very heavy drag 
put on the punch. 

Screwed shanks cannot be used when the shape of the 
punch is irregular, square, rectangular, Arc., as in such cases 
the punch must always have some particular position with 
respect to the ram, and the slightest deviation from this 
position will cause the punch to foul the die. With a 
screwed shank it would be very difficult to maintain this 
accuracy; but by means of a parallel shank, with a flat planed 
upon it, a set screw will secure it, in the same position 
accurately any number of times. When extreme accuracy 
is essential some arrangement of dowel pin can be easily 
devised upon the face of the ram to suit the special case, 
and for this purpose a jig should be made, so that the 
tools can be accurately made in the tool room to suit 
one or more presses in the shop, as may be required. One 
such arrangement is shown in fig. 76, where the punch 
P is secured to the ram by means of the parallel shank S, 
which is held by means of a set screw E pressing on the flat 
F. The punch, however, has a small dowel pin D fixed near 
its outer edge, and this entering the hole in the ram forces 
the punch to take up its proper position automatically, 
without any effort on the part of the workman fixing it. The 
dowel pin should have its upper end slightly tapered so 
that it may readily enter the hole in the ram, and should be 



74 MACHINES FOR SHEET METAL WORK. 




Fio. 76. 



mrf 



P i 



I 



METHODS OF FIXING THE BOLSTER. 



75 



made large enough to prevent its being damaged with 
ordinary shop usage. 

In an American cutting-out press the author noticed that 
the punch was fixed to the ram by means of a key similar 
to a method commonly used for attaching dies, but it does 
not seem to offer any advantages over the parallel shank 
type, except in some kinds of forcing work. For small 
cutting-out work, such as this press was intended for, it 
would be comparatively expensive to make, as well as more 
difficult to handle. 



6'. 



A good method of holding the bed is shown in fig. 77. 
The bolster B is fixed to the press by means of two set 
screws S, and the bed D is secured in its place by means of 
the key K, its position being adjusted by means of thin 
packing strips at P. This packing strip is also useful in 
case the key is not tight enough to hold the bed D securely. 

Another method of holding the bed is shown in fig. 78, 
where, instead of taper grooves, the bolster is planed with 
vertical edges and two set screws S are used to fix the bed 
in its place. This method is not so good as that shown in 
fig. 77, because there is nothing to ensure the block being 



76 MACHINES FOR SHEET METAL WORK. 

tightened hard against the bolster B; indeed, it may bo 
easily raised up slightly by the turning of the set screws, 
whereas the pressure of the key K and the taper grooves 




forces the bed down in a very positive fashion ensuring a 
solid fixing. The bolster is attached to the press frame by 
means of the dog plate E and a set screw in the way familiar 




to turners. This method of fixing gives more latitude in 
adjusting the position of the bed upon the press. 

When the die-forging is circular in shape, then it may be 
fixed as shown in figs. 79 and 80, by means of either two or 



METHODS OF FIXING CYLINDRICAL DIE. 



77 



three set-screws, which press upon the taper sides of the 
die. The three set-screws permit the die to be centred 
accurately in place very readily. The bolster may be either 
circular in shape or rectangular, and fixed to the machine, aa 
shown in fig. 77 or fig. 78. In the plan illustrated in fig. 77 




it is advisable to make the bolt holes in the form, of slots, so 
that the toolsetter may have some freedom iu adjusting the 
bolster in place. Washers should be placed under the head 
of the screw, so that the pressure due to tightening up may 
be distributed evenly. 



7s 



MACHINES FOR SHEET METAL WORK. 




Fio. 82. 



INTERCHANGEABILITY OF DIE AND PUNCH. 70 

A point of some importance to watch in the equipment of 
a workshop in which a number of presses are in use is the 
size of the dies and punches, so that as far as possible they 
may be interchangeable. Unless this is done much time 
will be wasted because a particular press is engaged in the 
execution of an order and cannot be stopped. In order that 
any machine of a group may be utilised, the stroke of the 
rams and the depth between the ram and the bed must in 
each case be noted, and the diameter and length of the 
punches determined to suit. If there is much variation in 
depth, then it may be necessary to construct home adapters 
to compensate for these differences. The tools should be 
constructed to suit the smallest machine, and for each of 
larger presses a plain chuck or false nose would be formed 
with a shank to suit the larger hole in the ram, and provided 
with a hole to take the standard punch. In the case of the 
die a special bolster would be required, the lower face or 
bottom being shaped to suit the press bed, whilst the upper 
part would be machined to take the standard die. By 
arranging the thickness of the bolster and the length of the 
false nose any variation of depth in the frames can easily be 
compensated for. 

By these means the shop foreman can easily arrange 
matters so that the machines are utilised uniformly, even 
when an unexpectedly heavy demand arises for some special 
article, the execution of which would be delayed seriously, 
possibly if only one press was available for that particular 
operation. An example of this interchange of tools can be 
seen in figs. 81 and 82 ; in the former is shown a punch 
and die fixed in a press of proper size, whilst in fig. 82 the 
same size punch arid die are shown fixed in a larger press by 
means of a false nose FN, and a thick bolster B, thus 
enabling the standard punch and die to be used, and the 
same sized blanks to be produced simultaneously at several 
presses. 



80 MACHINES FOR SHEET METAL WORK. 



CHAPTER VIII. 
ACCURACY AND DURABILITY. 

Tin: durability of dies and punches depends to some 
extent upon the nature of the work upon which they are 
used. Further, the work to be done by these tools governs 
the point as to the amount of accuracy and finish that shall 
be given to them. It is, therefore, necessary that care and 
judgment be exercised upon this point, for when the metal 
after being cut into blanks has to be stamped, or raised and 
clipped as often is the case, the cutting tools need not be 
so accurate as they would necessarily have to be if several 
pairs of tools were producing similar blanks, which may 
have to undergo many processes before finally coming together 
and be interchangeable when being assembled. The cutting- 
out tools for such articles as cycle chain links, quick firing 
shells, small arms ammunition, type writing machines, cycle 
and motor car parts, electrical apparatus, jewellery, locks, 
musical instruments, stencils, watches, or any similar 
delicate work, must necessarily be made very accurate and 
be of first-class finish ; whereas in the case of such articles as 
stamped hollow-ware, coal hods, elevator buckets, trunk 
trimmings, kitchen utensils, agricultural implement parts, 
hinges, lanterns, shovels, etc., a small fraction of an inch 
larger or smaller in the size of the cutting-out tools, or a 
slight variation in their shape would l>e of small consequence. 

STANDARD DIES AND PUNCHES. 

It is interesting to trace the process of making a die and 
punch to a standard pattern, such for instance as the two 
ordinary shapes, a pedal plate blank, fig. 83, and a spanner 
blank, fig. 84, the die D having been planed or milled 
both on the top and bottom and the necessary angle planed 
upon its sides to fit the bolster. The top of the die should 
now be cleaned oft* with a smooth file and emery cloth, after 
which the top must be smeared with sulphate of copper, 



PREPARING A STANDARD DIE. 



81 



a 

.wwwv 





D.I. 



FIG. 81. 



TWP 



82 MACHINES FOR SHEET METAL WORK 

commonly known in the workshop as "blue stone." This is 
done to enable a fine line to be seen, for without the 
blue stone, it would be of little use marking out a shape 
upon the bright face of the steel die with a marking scriber, 
because the lines could only be traced by the eye with great 
difficulty. In some instances the standard blank would l>o 
used as a template to mark out the shape upon the die, but 
this is not considered a good method unless a perfectly 
accurate blank is used as the template. Assuming that the 
blank is one that has been cut by a pair of ordinary press 
tools, probably it would not be accurate, therefore the 
better plan would be for the tool maker to carefully set out 
and mark the shape accurately upon the face of the die. 
This would be done with square, compasses, and scrilier, in 
a similar manner that a detail drawing would be made upon 
a piece of drawing paper. From this it follows that a 
knowledge of geometrical drawing is very useful to the tool 
maker. Having carefully indicated the outline of the figure 
by dots from a small centre punch, as much of the motal as 
possible should be removed by drilling various sized holes 
straight through the die ; the size of the drills used will 
depend upon the size and shape of the hole required in the 
die in other words the size and shape of the required blank. 
After removing as much metal as is possible by drilling, the 
die may be turned over and larger drills passed up the 
back to a certain depth, thereby forming a clearance ; this 
clearance will be seen in the section at h. 

If the holes have been carefully set out to follow the 
outline of the shape a little chipping with a thin flat chisel 
on top and bottom of the die will remove the bulk of the 
metal in one piece or lump. The back or clearance side of 
the die may now be cut away by the aid of larger chisels, 
after which the die is turned over in the vice so that the 
top, showing the outline of the figure, faces the operator, 
who will carefully chip and file out the shape of the blink 
by using the various small chisels and files. When the 
shape is apparently filed up true to the line, assuming that 
the pattern blank, fig. 85, is a true one, it is usual to try the 
blank upon the die, filing away the die until the pattern 
blank will pass into the hole. Suppose this has been done, 



CORRECTING THE DIE. 83 

and when the pattern is in the die and b l in blank comes to 
b in die, E 1 to E, and f l to /; now either turn the blank 
completely over, so that a comes to 6, b l to a, then E 1 will 
still be by E, as will also f l to f. This will show up the 
imperfection of shape in the curves of the die, and is known 
as correcting the die. Should the pattern blank pass into 




the hole and fit fairly well, showing no spaces when held up 
to the light, both when the blank has been passed in one 
way then the other, the blank and the d<e would be con- 
sidered sufficiently true for ordinary work; but if still 
greater accuracy is required the blank may be turned or 
swivelled round half a revolution, bringing E 1 to /, and f l to 
E, as this will give an additional test for accuracy. It is 
unnecessary to trace the making of the die, fig. 84, as that 
would be made in the same manner as fig. 83. One point, 
however, may be mentioned regarding fig. 84, namely : In 
the case of testing the die for accuracy the shape of spanner 




blank, fig. 86, would not allow the test of turning end for 
end, consequently the blank would merely be turned over, 
and tried in the hole of the die fig. 84. If the shape of the 
figure upon the die had been copied from a drawing or 
sketch, as would have been the case supposing there had 
been no pattern blank to work from, the mechanic who is 
responsible for making the die may either set out and file a 



84 



MACHINES FOR SHEET METAL WORK. 



template of sheet-iron, steel, or brass, or he may place a 
piece of sheet had on the die, tap it all over carefully with a 
small hammer, when it will be seen that the shape of the 
hole is formed upon the sheet lead. Now carefully cut 
round the lead with a penknife, thereby producing a sheet- 
lead template or pa'ttern, finally hammering the piece of 
lead straight through the die ; then turn the end for end, 




or over, as the case may permit, and try into the hole again 
in the manner before explained. The sheet lead method of 
testing dies is very useful, as by a little practice and care 
much time may be saved when a large variety of shapes and 
small dies are to be made time that would otherwise l>e 
taken up in making metal templates from iron, steel, or brass. 
Having made the die it may now be hardened and 
tempered, and attention may now be turned to the making 



PREPARING THE PUNCH. 



85 



of the punches, figs. 87 and 88 ; the punches will be centred 
on their faces at A A 1 , and centred at their shank ends. 
The shanks should be turned to some standard size, and the 
top and bottom faces turned or faced perfectly flat whilst 
they are in the lathe, and sulphate of copper smeared over the 
bottom face and the outline of the figure marked out with the 
scriber, using either the iron, steel, brass, or sheet-lead blank 




as a template. The punch may now have a groove planed 
or chipped all round (see figs. 87 and 88 at C). This will give 
a clearance so that the punch may be fixed upon the shaping 
machine in a special fixture (see fig. 89), and shaped up by 
the tool T; this will enable the bulk of the metal to be 
removed. The punch may next be carefully filed up to the 
lines marked vipon the face, and finally driven into the die 
about iVin., which will produce the required shape on the 



80 MACHINES FOR SHEET METAL WORK. 

end of the punch. The punch can then be put back again 
into the fixture, fig. 89, and carefully re-shaped, afterwards 
being filed until the punch passes into the die as freely as 
the nature of the work requires. The fixture for holding 
the punch upon the shaping machine, as seen at fig. 89, may 
be made in a variety of forms to suit the various require- 
ments. The simple cast-iron fixture, fig. 89, is easily made 
and suits ordinary work if the shanks of punches are all 
made to some standard diameter. The hole H and the slot S, 




enable a certain amount of spring or closing of the hole to 
be obtained, when the pin. is screwed into the lug /'-'. The 
pin IKISSCS through lug I 1 , and screws into lug/ 2 ; the 
washer W is placed between the two lugs to prevent too 
much strain being put upon the luga which might perhaps 
cause a break. This washer should lie made of such thick- 
ness that it is just sufficiently free between the lugs to 
allow the shank of the punch to be gripped firmly. 



INTERCHANGEABLE TOOLS. 



87 



CHAPTER IX. 
DIE MAKING BY DRIFT. 

As illustrating how any number of dies may be readily made 
to one standard size and shape, take the case of a cutting- 
out die for cycle-chain links. It is possible to make dies or 
beds of this kind by the hundreds, so that they shall not 
vary more than one thousandth part of an inch. Figs. 90 to 
93 show a good method of making these and similar tools. 
A standard bed and punch would first be made by the 
method described by figs. 83 and 84, for making standard 
dies and punches. The bed would be called the standard 
bed, and must necessarily be made very carefully ; in fact, 
both bed and punch must be made absolutely accurate, the 
punch being sized so that it can just be pressed into its bed 
or die, being what is known to a tool maker as a tight fit. 



r 




FIG. 90. 

Now, referring to fig. 90, the die is seen in plan at A, and 
the inverted plan B shows the bottom of the die ; between 
A and B the die is seen in section. Supposing this standard 
die to have been finished, hardened, and tempered, the next 
step is to prepare an accurate drift, with which it may be 
finished, or sized and corrected, so that all subsequent dies 
will be alike in shape and size. This drift will deal with 
the bar H H of the die, fig. 91. The method of dealing 
with the round holes or large ends of this die may for the 
present be left out of the question, as that portion of the 



88 



MACHINES FOR SHEET METAL WORK. 



work requires separate attention. To make the drift, 
procure a piece of tool steel about 3 in. long, and of such 
sectional area that will allow it to be shaped up for its 
whole length, the same shape as the hole in the standard 
die, figs. 90 and 91. Having first filed up the ends and 
covered them with sulphate of copper, mark out the shape 
on each end, and indicate by small centre dots, plane or 




shape it from cud to end by means of the shaping machine, 
afterwards carefully file it with suitable files until it is 
possible to pass the drift straight through the die with the 
assistance of light blows from a hand hammer. It is not an 
easy matter to make this drift, and it requires the greatest 
possible care and judgment to be exercised during each step 
in the process, and the micrometer gauge should l>e used 
throughout, for if the drift was carelessly driven through 



FORMATION OF DRIFT. 89 

the standard die a tight driving fit it would be liable to 
burst the die, in addition to the drift being so ripped and 
knocked about as to make it absolutely useless. 

The standard die, fig. 90, is used more as a guide to 
shape, and to enable the extreme ends of the drift to be 
fitted with the die, rather than to be used for forming the 




general shape of the drift for its entire length. This must 
be done by careful filing, when the drift has been made 
perfectly parallel and of uniform shape. The next step will 
be to file a clearance or taper for about half its length, 
leaving l|in. parallel. At the end of the clearance make a 
distinct bevel, so that a hammer may be used freely upon 
this bevelled end, which may now be called the head of the 
drift, seen at T, fig. 92. At the other end of the drift it 



'.'0 



MACHINES FOR SHEET METAL WORK. 



will l>e necessary to file away the centre S, in the manner 
shown at fig. 92, thereby forming two small horns 6. These 
horns are important to the successful use of the drift, as 
their office is to fit round holes iu the die, thereby guiding 



F 2 





the drift, and helping to keep the drift perfectly perpen- 
dicular, whilst the bar part of the drift is rectifying the bar 
part of the die. The drift being finished may now be 
hardened aud tempered its entire length to a dark straw 
colour, and attention may now be directed to the use of 
this drift. 



PREPARING DIE FOR DRIFTING. 



91 



The die, fig. 91, having been marked out and had the two 
larger holes drilled by a method that will be explained later, 
it will be seen that these two larger holes represent the ends 
of a cycle-chain link. The drilling of these holes will leave 
a distance between them in the form of a bridge, from hole 
to hole. This bridge is known as the bar part of the die. 
To remove the metal of this bar, first drill two small holes 
H^ H, fig. 91 (C), either by the use of a special jig or other- 
wise, then plug up these two small holes by driving in soft 




FIG. 94. 

iron wire, and file them off level (see section of die at D). 
Having plugged the small holes, a third hole may now be 
drilled directly in the centre (see section of die at E). Now 
remove the part of the plugs that remain, and carefully chip 
and file away the bar, leaving a few thousandths of an inch 
to be removed by the drift. Fig. 92 shows the die in 
section, and it will be noticed that the drift is in position 
ready to be driven through. Another section is shown 
at F 2, fig. 93; and a third section of the die, F3, shows 
the centre or bar part of the drift only as it passes through 
the die. 



92 MACHINES FOR SHEET METAL WORK. 

The standard die or Ixjd, fig. 90, may be kept and used 
to finally correct all punches before they are hardened and 
tempered. The various stages of machining the cutting-out 
punch is shown at fig. 94, where P is a steel forging, which 
has been centered and had its shank truely turned, and the 
required shape dotted out upon the cutting end. The 
punch may then be placed in the special fixture seen at fig. 
S9, to enable the part e at P 1, fig. 94, to be milled away. 
This would be done with the cutter A lt an ordinary milling 
cutter. Passing to Pj 2,, it will be seen that the ends d l d t 
have been milled away with the milling cutter B. The 
punch may now be carefully fitted into the standard die A, 
fig. 90, by means of filing. 

The complete set of tools for piercing the two holes in a 
driving chain link are a good example of accurate tool 
making. These tools illustrate the application of steel 
bushes for accurate piercing. A bolster B, fig. 95, planed 
top aud bottom, and having two holes, one of which is seen 
at X, drilled and tapped, is ready to receive the pin, fig. 100. 
Two such pins serve the double purpose of setting up the 
small piercing dies, 0, P, fig. 95, and allow the piercing bits 
or small blanks to drop through the long hole that is drilled 
through the centre of the pins for this purpose. The 
die holder D H receives the piercing dies O, P, which are 
held in position by a small set pin, seen in the part section 
of the die at fig." 95. The die holder D H is fastened to 
bolster B by four screws. The false nose or punch holder 
F X is made from a Bessemer steel forging, shaped out to 
receive steel pieces A, B, and C. These re held in position 
by set screws. Another thinner steel piece I) is fitted into 
the punch holder, and hardened to receive the thrust from 
the punch ends when they are piercing blanks. 

The thickness of steel piece B determines the centres of 
the punches, since the holes for receiving them are drilled at 
the point where the faces of A, B, and C come together. 
After the punch holes have l>eeu drilled in steel pieces A, B, 
and C a little would be filed oft' the faces F 1, F 2, F 3, F 4 (see 
fig. 99). This would enable the pieces A, B, and C to firmly 
grip together the punches, when the set screws shown at fig. 95 
are screwed up firmly. A plan and inverted plan of the punch 



COMPLETE SET OF PIERCING TOOLS. 

'<,- li J 




MACHINES FOR SHEET METAL WORK. 



..Jt- 



- T 

*"*f 

A 



F N 



C H 



D.H. 



4' 3" 

FIG. 06. 



.J. 




STKIPPER AND GUIDE PLATES. 



2l 



Jc i*' - 



o o 



rr 



\d 



P4 



-e- 



P. 2 


,T 


4y 


- - T - % 


\ 


1 



T 

IS 

_1 

T 



P.I 

-Oh 



CO 



1 



Fio. 98. 



% MACHINES FOR SHEET METAL WORK. 

holder is seen at fig, 97. The clearance holes C, H are to 
allow the punch holder to come down close to the stripper 



-J 






:: 



FIG. 99. 



plate, and in doing so to clear the uuts_ of the stripper bolts 
N, fig. 101. Unless these holes were 'drilled in the punch 
holder it would be necessary to let ;the piercing punches 




Fio. 100. 



stand out further, probably causing them to spring during 
working. The guide plate* P 1, fig. 98, guides the blank and 



AUTOMATIC KNOCK 'OUT OR FLIPPER. 97 

holds it in position whilst it is being pierced. P 2 is a 
packing plate, and P 3 is another plate, which has a slot in 
it to receive a small tongue piece and spring, and is known 
as the knock-out or flipper, their office being to extract and 
throw the blank from the tools after it has been pierced. 
The plate P 4 serves the double purpose of guiding the 
piercing punches and stripping the blank from the punches 
after it has been pierced. The four plates PI, P 2, P 3, 
and P 4 are all bolted to the top of the die holder in the order 
of their numbers, thereby forming a complete set for holding, 
piercing, stripping, and extracting the blank from the tools. 
The author's object in giving the chain link as an example 
of cutting and piercing, is that he considers it to be a class 





of work requiring exceedingly accurate workmanship. It 
therefore forms a good specimen for the student to investi- 
gate, and on several of the sketches are given the actual 
working dimensions, thereby enabling the student to use 
them as a guide in designing similar tools to be applied for 
other purposes than the chain link blank. 

A complete set of tools for cutting out a chain link are 
shown in figs. 102 to 106. The combined die holder B 
receives the die D, which is keyed in position by K, the strip 
of metal from which the blanks are cut being fed into the 
tools by the feed rolls R, R. The making of these punches 
and dies has been explained in reference to figs. 90 and 94. 
The combined metal guide and stripper, figs. 104 and 105, 
is fixed upon the bolster by the double-screwed pins, one of 
which is seen at fig. 104. The short end of these pins is 
screwed into the holes A, A of the die holder B (see fig. 103), 
and the stripper plate can be raised or lowered at will over 
the top of the die D by means of the two lock nuts (see fig. 
8wp 



MACHINES FOR SHEET METAL WORK. 

-! 




Fio. 102. 



.1 



m 



i 



SET OF BLANK CUTTING TOOLS. 



99 



104). G, G are the guides shown on the inverted plan. 
Reference to this useful type of combined guide and stripper 
arrangement will be made in a subsequent chapter on tool 
setting. 

rrrra 



n 


c 


CO 


c 


n 




Another interesting example of the use of steel bushes for 
accurate production is the drilling of a small chain block of 
figure 8 section. The tools for this operation are seen in 





detail, figs. 106 to 110. The centres of the holes to be 
drilled in the block are '4 in., and these centres are obtained 
by means of the small steel bushes. The centres may be 



100 



MACHINES FOR SHKET METAL WORK. 



reduced or increased by a method which will be explained in 
another chapter. Referring to fig. 106, a plan C, a side 
elevation B, and an inverted plan A of the complete jig are 
seen. The block to be drilled is held firmly by the thrust 
from the end of slide S, which is screwed up by the handle 
H. At fig. 107 the jig is seen in position upon the table T 




Fio. 1C6. 

of a vertical sensitive drilling machine, ready to receive the 
drill through the jig bushes. The drill is held in the drill 
chuck D C by a very simple and reliable means. It may 
here be mentioned that in the case of the ordinary and 
well-known types of self-centreing chucks, as used by tool 
makers and machinists, two and sometimes three jaws are 
brought together by small screws. Although these are very 



SPECIAL DRILL CHUCK. 



101 



useful and reliable when in the hands of skilled mechanics, 
they may become a source of trouble and expense when in 
the hands of unskilled labour. There are instances where 
unskilled labour have the setting of their own drills, and 
where the required rate of cutting makes it very essential 
that the drill be gripped very firmly on account of the rapid- 
cutting action of the drill, tending to cause the drill to 
rotate in its own chuck. This necessitates a strong, cheap, 
and reliable chuck being placed into the hands of the 
operator. Such a chuck is seen at fig. 108, where the drill 
is received into a long bush B, having one side cut away 




after it has been drilled to receive a separate piece K. The 
set-pin for gripping up the drill is brought against the back 
of K, there being a flat filed vipon K to receive the thrust 
from the end of the pin. This form of chuck will stand a 
great amount of rough usage without getting out of order. 
Fig. 109 is the guide-thrust plate, used for setting the 
block into position. The plate is first drilled, as shown, 
afterwards being shaped away to fit the shape of the block 
(see F, fig. 109). The thrust slide S of this drilling jig is 
shown at fig. 110, there being three views: a side elevation 
S 1, an inverted plan or view of bottom 1 P, and a plan or 
top view P. 



102 



MACHINES FOR SHEET METAL WORK. 




O 
O 



Fio. 100. 



AUTOMATIC UMBRELLA STRETCHER MACHINE. 



103 



An example of wire-working tools, as showing the applica- 
tion of the punch and die for such work, is seen in fig. 111. 
The complete set of punches and dies are shown for 
automatically flattening, double piercing, and cropping or 
cutting off an umbrella stretcher. The wire at the top of 
the drawing gives the four stages A, B, C, D in the progress 



S E 





of the work. The wire is fed through the machine by means 
i-feed, which is worked by a crank and connecting 



of a grip- 
rod. Th 



rod. The stroke of this crank can be varied at will, and the 
length of stroke given by the crank will determine the 
length of the finished stretcher. The blocks or castings 
carrying the tool slides, into which the various tools, punches, 
and dies are fixed, are necessarily set a certain distance 
apart, suitable packing pieces being used to give the 
required distance. To deal with each length of stretcher 



104 MACHINES FOR SHEET METAL WORK. 

that is being made on the machine the plate-iron 
pieces are dropped between each set of slide blocks. The 
four sets of slides are worked by levers and rollers ; they 
are connected to act at the bottom of the slides, and are 
actuated by means of cams and cam shaft working under 
the bed of the machine. Beginning at the right hand side 
of the drawing, h'g. Ill, the flattening punches are seen nt 
A. They are ground upon their ends to produce the 
flattened shape seen on either side of the wire. The second 
and third set of tools are the two sets of piercing tools. 
Each die is backed up by a long set pin, which is used for 
setting up the dies, a hole being drilled through the centre 
of the pin, through which the piercing bits pass and drop 
into an iron box. The fourth and last set are the cropping 
tools. The cropping punch is shape'! upon the end to the 
exact shape necessary to remove the bit of scrap to form the 
two ends of the stretcher. The cropping die is of peculiar 
and novel construction. It is formed or built up by placing 
two pieces of round steel at a certain angle so that when 
they are moved forward by the set pins at their back ends 
the distance between their cutting ends will be reduced. 
This may sometimes be necessary, should it be desired to 
make the punch and die a better fit The cropping punch, 
when being made, can first be roughed out, then put into 
the machine, and carefully worke-i up against the cropping 
die so that the two pieces of round- steel which form the die 
would gradually cut away the end of the punch into the 
required shape. 

Upon the extreme left of the drawing, fig. 1 1 1, the end 
views of the four sets of tools are seen. A very neat 
arrangement is here shown for fixing and adjusting the small 
piercing punches. A taper hole is bored in one end of the 
slide, and in the other end a larger hole is drilled and tappet! 
to receive the punch-holder. The holder is bored for a portion 
of its length to receive the piercing punch. A clearance hole 
is then put in for the remainder of its length to receive a long 
thrust rod, and finally the back end of the holder is tapped 
to receive the backing-up set pin S P, after which the 
punch holder is sawn along one side of its taper end, as seen 
in the end view. From this it will be readily understood 



CONSTRUCTION OF CROPPING DIE. 



105 




106 MACHINES FOR SHEET METAL WORK. 

that if P H be unscrewed, say half a revolution, this liberates 
the piercing punch. The lock nut L N can now be loosened, 
and thi punch advanced as required to enter the die by 
means of the backing-up pin S P, after which L P can be 
locked "gain, and finally the punch holder P H can be 
screwed into position, thereby forcing the taper end of 
the punch holder into the taper hole of the slide, and 
closing the ends of the punch holders firmly upon their 
respective punches. All four sets of tools ran readily be 
adjusted whilst the machine is in operation. 



CHAPTER X. 
METAL SPINNING. 

METAL shells, after being cupped, drawn, or raised, have 
sometimes to be expanded, necked, bulged, or otherwise 
altered in shape. In some instances this is done by means 
of special expanding dies, and closing, necking, or reducing 
dies ; but usually the operations of bulging or necking are 
performed in the spinning lathe. The lathe consists of a 
bed fitted with a fixed headstock, which carries the chucking 
mechanism for receiving such articles as are seen at A, B, 
C and D, fig. 112. These represent common examples of 
spinning. They are held in position by a moveable tail 
stock. The spinning operation is usually performed by 
special burnishing or friction rollers, these being carried 
upon a compound slide rest. The pressure of these rollers 
or burnishers against the article forces the metal to flow into 
the desired shape, the outline being governed according to 
the point at which the pressure of the rollers is brought 
upon the article. The examples E, E 1, F, F I, fig. 112, are 
of cornish-pole end stampings, the small amount of spinning 
required on these being to connect the two halves together. 
This would be done by fixing one half of E or F in the 
chuck, and expanding a little at or L by means of a hand- 
xpinning tool. Then E 1 or F 1 is taken up by the hand to 
insert P into 0, or M into L, after which O or M is rolled or 



EXAMPLES OF SPINNING OPERATIONS. 



107 




108 



MACHINES FOR SHEET METAL WORK. 



spun over P or L, as the case may be, by exerting a slight 
pressure upon the metal by means of the hand-spinning tool. 
The various stages of this method of spinning are shown at 






nn 





A, B, C, fig. 113. The first shows E and F alike. In the 
second stage E is seen to have been expanded, whilst F has 
been inserted into E, and in the third stage E has been 
rolled or spun over F. Another example of joint spinning, 





where the metal is turned down at a sharp angle, is 
seen at fig. 114. A copper float ball for a water cistern and 
tank work forms a good illustration of jointing (see fig. 115), 
where A and B are portions of hemispheres which are 




jointed together to form the sphere. Hemispheres A and B 
are both drawn or raised in the same die, afterwards the edge 
of one is trimmed off in a slitting shear machine, and when 
A^and B are joined together the broad edge E overlaps the 



SPINNING ORNAMENTAL WORK. 



109 



smaller edge F. This rolling or spinning joint metal work 
is done in many different styles, and by the assistance of 
quite a variety of special tools, but figs. 113, 114, and 115 
will serve to illustrate the principle upon which the spinning 
is carried out. 

Much of the ornamental work, such as bedstead knobs 
and similar mounts, used for central and end embellish- 




ments, are changed in form after they have left the drawing 
press, by means of a simple high-speed lathe containing a 
former in the end of its spindle (see fig. 116), where the 
arrangement is that a spindle S carries a former, which goes 
inside the work to be shaped. The metal cup C has been 



110 



MACHINES FOR SHEET METAL WORK. 



drawn in a press, and is about to be shaped to the former 
F, which is made sufficiently small in diameter for the 
purpose. Its largest diameter must never exceed the 
smallest diameter in the work to be shaped, or the articles 
shaped thereon could not be drawn off when finished. A 
simple roller R is used, mounted between the forks at the 
end of a suitable lever. This lever will be seen at fig. 117, 
and it would be worked preferably by the foot. The 
contour of the roller corresponds with the shape of tho 
exterior of the finished article, only it may be much 
larger in diameter. 




Fio. 117. 

The partly-formed article is slipped on to the former, and 
held against it, whilst the pressing on the end of the lever 
at E causes the external roller R to force the sheet brass to 
the form of the central mandril, or former F. This causes 
the work to rotate, and by this means swells and indents can 
be rapidly formed on any raised or drawn article, and the 
cost of labour is very trifling. Not only can plain swells 
and indents be formed, but ornamental work can be done, 
such as milled edges, either straight, crescent shaped, spiral, 
or in the form of heads ; in fact, this arrangement enables 
many designs to be produced that cannot be done by any 



SPINNING A RIVET HEAD 



111 



other way but casting, and it has the great advantage of 
cheapness as regards the tools, another advantage being that 
skilled labour is not required to work the tools. Referring 
again to fig. 116, when the article C has been shaped by the 
action of the rolling, the finished diameter of the cup 
must be sufficiently large to enable it to be readily removed 
from the former. In other words, the diameter of the 
part of the cup C, made by A on the roller R, must be large 
enough when finished to pass over the diameter of part B on 
the former F. This will be done by commencing with the 
proper sized cup, according to the shape of the article, and 
the amount of rolling required. 

The operation of spinning the end of a wire rivet so as to 
form a head is a novel example of the useful application of 
spinning rollers. Fig. 118 is one of two chucks that would 
be employed in spinning both heads H, H 1 of the rivet A. 




The chuck at K is screwed into the spindle of a small 
special lathe, the coned part E also fitting the spindle. The 
front end of the chuck is slotted to receive rollers L, L, and 
when these two rollers come together in the chuck (the 
centre point C of the rollers L, L comes exactly in the 
centre line of the chuck itself) each roller is curved on one 
edge, so that when the two come together in the position 
shown, the curved form on the two rollers shall be the curve 
that is required upon the head of the finished rivet. These 
rollers rotate upon the pin F, which is made a driving fit in 



112 



MACHINES FOR SHEET METAL WORK. 



the chuck, bat a loose fit in the rollers, and secured 1>\ tin- 
nut S. Assuming the chuck and rollers to have been fitted 
up perfectly true, it will be readily understood that, when 
the whole rotates together, the joint line C between the 
rollers, and the centre of the transverse hole in the rollers, 
will both be in perfect alignment, with the centre line 
through the chuck and lathe spindle. 

Now, supposing two such chucks and their rollers to be 
mounted on the lathe and rotated at a high speed, if the 
rivet B, fig. 118, be held perfectly central and firmly 
between the two chucks, and the chucks pressed up against 
the ends of the rivet B, the result will be that the rollers 
L, L will rotate in opposite directions, and a very light 




pressure will cause the rollers to spin over the ends of the 
rivet, thereby forming the heads H, H (see rivet A, fig. 118) 
where the rivet has been headed. This arrangement has 
been used extensively and successfully in connection with 
the manufacture of driving chains, in preference to riveting 
by means of either a hand hammer or power hammer. 



SPINNING A SHEET STEEL CUP. lib 

Another example of spinning (see fig. 119) further illus- 
trates what actually takes pkce during the operation of 
spinning sheet-metal articles by means of rollers in a lathe. 
A chuck M is mounted upon the spindle of a vertical drilling 
machine, and a pin P is driven through the chuck to carry 
the rollers R, R 1 . A steel cup C B, which has been previously 
drawn and pierced, is placed in the holder K, fig. 120, after- 
wards the holder and cup receives a cylindrical plug. 
The holder K is held by being fixed between the vice jaws 




FIG. 120. 

(see fig. 120). The cup C B has a curved end, and is exactly 
the shape that it would be when it leaves the cupping tools 
(see fig. 121). 

Now, having secured the cup C B, the plug and the 
holder K all in the vice, so that the centre of the cup C B 
stands directly under the centre of rolls R, R 1 , if the 
spindle and chuck are rotated, and the rolls R, R brought 
down upon the end of the cup, they will roll in opposite 
directions, and roll or spin the end of the cup perfectly flat, 
as seen at C A, fig. 119. The cylindrical plug A forms the 
anvil, and the curve on the end of this plug governs the 
inside shape of the cup. 
9wp 



114 



MACHINES FOR SHEET METAL WORK. 



Fig. 122 is a useful and cheap form of chuck, which may 
be made of either cast or wrought iron, and used for 
chucking cups of this kind to enable them to be operated 
upon by turning tools in a lathe. A section of the chuck is 
given, from which its form will readily be seen. After being 
screw-cut at N to fit any lathe spindle, it is bored out at L 
to receive the cup C A ; it is also counter-bored as large as 
possible (consistent with strength) in the centre of its length 
to ensure of the chuck springing at T when under pressure 
of the pin collar C of the pin P. A hole V is drilled at 
right angles to the pin hole, a slot S being afterwards sawn 




O 



I 1 



from the front of the chuck into the hole V. The fact of 
the metal chuck being comparatively thin at T, assisted by 
the hole l)eing drilled at V, ensures sufficient springing of 
the chuck under the pressure of the pin P to tirmly grip 
the cup CA. Chucks of this type may be quickly altered 
by re-lx>ring to accommodate a new size of cup, or they may 
be completely faced oft' at the front end when worn down 
and l>e again re-lx>red to suit a smaller-sized article. 

The process of building up a roller-chain link having separate 
losses will serve as an example to show how the extracting 
mechanism may be actuated by the slide of a power press ; 
at the same time the usefulness of the power press, as a 
means of reducing the cost of production, may be seen from 
this operation. 



SPECIAL FORM OF CHUCK. 



115 




c 

FIG. 122. 



O O 00 O (Q 




ill ill Tun m 

FIG. 123. 



116 MACHINES FOR SHEET METAL WORK. 

Referring to fig. 123, it is required that the blank A 
shall have the metal so cut away from one side as to 
form two small bosses. To do this the blank is first pierced, 
it is then fixed upon two pegs in a lathe, whilst a special 
milling cutter is brought up against one of its sides to remove 
the metal from the centre (see fig. 123 at B). Finally, 
another smaller milling cutter forms the two bosses 
separately, to complete the bosses as seen at C. From this 
it will be evident that to make large quantities of similar 
plates would, in addition to being a great waste of metal in 
forming the bosses, necessitate a large number of small mill- 
ing lathes being employed for the operations, besides using 
up quantities of cutters. It was to overcome tliese difficulties 
and to make the production cheaper that the tools seen at 
fig. 124 were introduced. Passing to fig. 125, another blank 
A is seen, this time cut from metal of suitable thickness as 
required for the finishd article. The blank has two holes 
pierced in it, equal in diameter to the outside diameter of 
the required bosses. Two pieces of cylindrical steel E, E are 
cut off a bright rod, and forced into the blank A. The next 
operation will be to use the tools as seen at fig. 124 to 127. 
These tools are fitted in a heavy double sided power press. 
The construction of the punch holder, die and die holder, or 
the methods of holding the punches and dies needs no ex- 
planation, these having been previously described iu chapter 8. 

Referring to fig. 124, a slot is planed straight across the 
bolster K, to receive the square piece of steel H, and when 
H is allowed to fall so as to reach the bottom of the slot the 
two steel pegs E, E are pushed down the holes of the dies. 
These steel pegs E, E are <>f such length that when one end 
rests upon the top of H the other end stands below the top 
of the die. The correct distance that E stands below the 
top of die is a little less than the length of the boss E on the 
blank B, fig. 125. From this it will be evident, by referring 
to figs. 124, 126, and 127 that when H, E, E are in their 
lowest position the two bosses E, E could be dropped into the 
holes of the die, leaving the blank on the top just clear of 
the die. The press is next moved through one revolution of 
its crank shaft, (hiring which time one down stroke and one 
up stroke are made : on the down stroke centre punches P, P 



EXTRACTING MECHANISM ACTUATED BY RAM. 



117 



will punch the centre holes 0, of the blank B, fig 125. The 
process of punching these centre holes will expand the small 




bushes E, E, fixing thf-m very firmly in their respective holes 
in the blank. 

These centre holes will afterwards serve to guide the drill 
for drilling the first sized hole in the bosses previous to their 



118 



MACHINES FOR SHEET METAL WORK. 



being finally corrected by a second drilling in a suitable jig. 
Upon the up stroke of the press the rods R, R, which are 
connected to the slide, would lift H, E, E, and thereby extract 
the article B from the die ; B will now fall from the tools. 




It will be noticed that the slide is shown in fig. 124 upon the 
top stroke, and the question may be asked, how can the 
next blank and pair of small bushes be placed into the die 
when the pegs E, E project above the top of the die 1 The 



o 




o 



answer to this question will explain the value of the arrange- 
ment. As a matter of fact, the rods R, R are shown set in 
the wrong position, and to set the rods properly for the 
work now being performed in the press the nuts N, N must 



SETTING THE EXTRACTING MECHANISM. 



119 



be unlocked, and rods R, R unscrewed sufficient to allow H 
and pegs E, E to fall down into such a position as to bring 
the tops of pegs E, E a distance below top of die, equal to 
about one-sixth the length of the bosses on the blank. This 
will allow the small bosses to be placed in the die, then when 
the punches come down in their travel they will force the 
bosses into the die until neither bosses, pegs, or H can be 
driven further. The punches will then complete their work. 
From this it will be seen that by lengthening or shortening 
rods R, R the bar H can be placed in any relative position 
when the slide is on the top of the stroke, these relative 
positions being obtained by giving more or less lost motion at 



iiB 



the heads T, T of rods R, R during the up stroke. When H 
falls upon the bottom of slot in K if the press slide has not 
completed its down stroke the heads T, T will leave the 
steel anvil H. Therefore, whatever distance there is between 
bottom face of anvil H and the inside shoulders of heads T, T 
will be lost motion to anvil H upon the return stroke, because 
heads T, T must necessarily travel some distance before com- 
mencing to lift the anvil H. Fig. 126 is a plan and fig. 127 
an end elevation of the die and bolster, tig. 128 being an 
inverted plan of the chvick for holding the punches. This 
principle of extractor can be greatly modified to accommodate 



120 MACHINES FOR SHEET METAL WORK. 



V 






> 




TOOLS FOR BENDING WIRE. 12 

the various requirements in either hand or power presses to 
suit different classes of work. 

The bending of wire and metal strips usually refers to 
articles which have their surfaces moved into some new and 
permanent shape without their thickness being materially 
altered. They may, however, sometimes be slightly 
thinned at certain points, where the action of the bending 
tools have stretched them in bending a corner to some sharp 
curve or angle. When bending wire or strip metals it is 
sometimes difficult to decide upon the correct shape of tools 
to give the desired effect, since the metal will frequently 
spring back from the shape to which the tools have bent it 
part of the way towards its original shape. This is due to 
the elasticity of the metal, and varies according to its 
nature and temper. Lead and copper will give very 
little trouble in this way, but brass, iron, and steel are not 
so easy to manage. Fig. 129 represents a pair of tools 
for bending the steel wire D, D. The punch P, and the die 
D, would be made to press the wire into the form seen at 
N 1 , N 1 , but the wire, after being removed from the bending 
tools, would spring at the corner C into the position D, D. 
From this it will be readily understood that the bending 
tools must necessarily be made to bend the wire a sufficient 
distance to allow for its springing back. This frequently 
necessitates the altering of the curves on the bending tools 
after they have been tried. In the case of fig. 130 the 
springing action referred to would take place at both 
corners, C, C, the tools having been designed to carry the 
wire down to the shape shown at dotted lines N 1 , N 1 . The 
final outline of the article after the springing has occurred 
is indicated by D 1 , D 1 . 

Fig. 131 illustrates the bending of a flat steel spring, 
S S. When bending curves and angles, similar to those 
contained in this kind of work, the springing back difficulty 
must necessarily be overcome by careful experiment. In 
addition to this, it is often advisable to ease away the tools 
at certain points. It would appear to a new beginner that 
the proper way to construct such tools would be to make the 
face of the bending punch P, and the face of die D, to fit 
the top and bottom sides of the spring respectively, so that 



122 



M \< IIINKS KOK SHEET METAL WORK. 



when the bending tools are well up to their work the metal 
of the steel spring exactly fills the space between the faces 
of the punch and die. It is, however, found in practice to 
lie much better for the working of the tools if they are 
eased off at certain points where the action of bending does 
not actually occur. There are several reasons for this. A 



C C 

Fio. 130. 



little dirt may accumulate in the tools, the metal may not 
always be of an exact uniform thickness for its whole area, 
or the peculiar shape of the curves upon the tools may \>e 
such as to make it difficult for the toolmaker to ensure the 
tools fitting accurately the curves on either side of the 
metal spring, thereby leaving the exact same space between 
the tools for the whole length of their curves. This is a 



FORM OF TOOLS FOR METAL BENDING. 



123 



difficulty that could be overcome by careful toolmaking, but 
the rough nature of the work will scarcely warrant the 
expense of such care as would be required to carry this into 
effect. Particularly is this so by reason of the fact that by 
easing away the tools as before mentioned enables the 
bending to be done with very much less power required for 
the operation. Taking the case of the spring S, S, the 
punch would need to press hard at A, A, also at the 
bottom B, but it would be advisable to ease the punch away 
well at E, E, and it will further be noticed that the die has 





been eased away at two points a little below E, E, where a 
clear space is shown between the bottom of the spring and 
the die. 

It frequently happens that large quantities of short 
lengths are required to be cut from loutr wire rods. An 
instance of this kind would occur in a hinge factory, where 
joint-wire rods would be required for connecting the two 
sections of the hinge together. There are also instances 
when wire rivets and similar wire lengths are required to be 
absolutely square at their ends when cut, and to be of 



124 



MACHINES FOR SHEET METAL WORK. 



standard length. Figa. 132 and 133 represent suitable 
tools for cutting wires of this kind. The casting C forms 
the bolster, and it is bored to receive the die D. This die 
is drilled straight through, parallel, to receive the wire W 
an easy fit. The die D is held firmly in position by set 
pins, which are screwed into the luas L, L. The set pins 
are not shown in the sketch. Another part A, of the bolster 
C, is drilled and tapped central, and in perfect alignment 




Fio. 132. 



with the hole in the die D, to receive the set pin S, which is 
locked in position by lock nut L N. This set pin may be 
adjusted to form any given distance between the end of set 
pin and face of die. If cutting rivets f in. long the 
distance between end of set pin and face of die will be set 
at in., so that set pin S acts as a stop gauge, to which the 
wire is pushed by the hands of the operator 

The punch P, fig. 133, works up and down close against 
the face of the die, and is slotted for a distance up to pass 
freely over the wire. The top of this slot is made the form 



PRESS TOOLS FOR WIRE CUTTING. 



125 



of the wire to be cut so that the action of the punch, 
whilst chopping or shearing, shall not damage the wire. The 
die is made double ended (see fig. 132) so that both ends 
may be ground and used in their turn ; and the fact of the 
die being a comparatively good length holds the wire 
sufficiently steady and -square, although the wire may be an 
easy fit. Another example of chopping or shearing a rod is 
seen at fig. 134. II is a bright drawn steel rod, and would 




probably usually be supplied from the wire drawn in 12 ft 
lengths. These rods, which are fig. 8 in section, will be 
finally sawn up into short pieces by means of slitting saws 
operated in a milling machine, but the 12 ft. lengths would 
be awkward to handle in the machine. They are, therefore, 
usually chopped or sheared up into, say, 4 ft. lengths, to 
enable the milling machine operator to handle them easily. 
The bottom shear blaHe B, would be about f in thick, and 
bolted on to a special bolster by bolts passing through holes 



126 



MACHINES FOR SHEET METAL WORK. 



A, A. The punch P is about f in. thick at part T, and 
hollowed out the same as B to fit half section of the steel 
rod R. These tools may be fitted to either a hand or power 
press, and the face of P would slide up and down against 







face of B, in the position as shown in fig. 134, thereby 
forming an efficient form of chopping or shearing set of 
tools. Both punch and die may be made perfectly square, 
no bevel being required upon either. 



DRAWING AND RE-DRAWING. 



127 



CHAPTER XI. 
DRAWING AND RE-DRAWIXG. 

DRAWING proper refers to the cupping of a blank, as in 
cutting and cupping processes, or in taking any piece of 
sheet metal in the form of a blank, and producing therefrom 
any cup-like shape during which process a flowing of the 
metal takes place. 

The term re-drawing applies to any subsequent drawing 
processes that follow the first drawing or cupping process as 
would occur in the manufacture of a cartridge shell or 
similar work. For instance, if any blank be cupped it may 




FIG. 135. 

be said to have been drawn or had its first drawing. But if 
this same cup be further reduced in diameter by being 
passed thi'ough a second pair of tools, then the process of so 
reducing it will be called re-drawing. 

Referring to fig. 135, we have two blanks and their 
respective cups, No. 1 and No. 2. The first, or No. 1 blank, 



128 



MACHINES FOR SHEET METAL WORK. 



is l|f in. diameter, and cut from metal '111 in. thick, it has 
been cupped by a cupping punch '629 in. diameter, and a 
die bored out to "818 in. in the hole, the thickness of metal 
has been reduced from -111 in. to -0945 in. during the 
cupping process. There has, therefore, been '0165 in. draw- 
on the metal by means of the cupping tools. In the case of 
No. 2 the blank is -113 in. thick, it has passed through a die 
having a hole '878 in. diameter, the drawing punch being 
680 in. diameter, there has been OH in. draw on the metal. 
Had the punch been 652 in. diameter, the blank would have 
merely passed through the die, coming from the tools in the 




form of a cup without any draw or flow of the metal taking 
place. From this it will be readily understood that in any 
case of drawinsr an article each process must be considered 
separately. The thickness of the metal blank and the 
outside diameter require'! for the cup are the two points 
that decide the diameter of the hole in the die. Then twice 
the thickness of metal blank subtracted from the hole in 
the die will give the diameter of the cupping punch, if no 
draw or flow of metal is required. But should it be required 
to reduce the thickness of metal during the cupping process, 
then twice the required reduction of the metal thickness 
must be added to the diameter of the punch. In cases 
where the size of the hole in the cup is the more important, 



RADIUS ON DRAWING PUNCH END. 129 

then the order of things will be reversed, the drawing being 
arranged by the diameter of the hole in the die the larger 
the hole the less the draw, and the smaller the hole the 
more will be the amount of draw on the metal. A blank 
and its cup is seen at fig. 136; it will be noticed that the 
bottom of this cup has a rather sharp corner ; this is a point 
that is governed to a large extent by the shape of the punch. 
If a sharp corner is required on a cup the end of the drawing 
punch should be finished by having a small radius on its 
corner, whereas if the radius on the corner at the 
end of the drawing punch be made comparatively larger 
then the corner of the closed end of the drawn cup 
will necessarily have a larger radius. In conical drawing 
the taper punch forces the blank into a taper die, 
after which the conical cup will be extracted or lifted 
from the die, either by the operator's hands or some form 
of extracting mechanism. The drawing of conical work 
may in a sense be called raising, in fact, it is at times very 
difficult to distinguish drawing from raising, because amongst 
the great varieties of metal work one blank may be stamped 
or raised in a stamp, whilst another article exactly the same 
shape may be raised in a power press, the article passing 
in and out of the die not through the die yet a certain 
amount of flowing may have taken place in the metal whilst 
the article was being formed into shape, which would 
probably warrant the term drawing being applied to the 
process. 

Fig. 137 was made in combination tools, the blank being 
cut out, then held by the cutting-out punch under pressure, 
whilst the drawing punch (which may in this case be called 
a raising punch) comes down and draws or raises the 
blank into the shape, the article being afterwards pushed 
up and out of the die by an extractor. A somewhat similar 
example to fig. 137, but of smaller size, is shown at fig. 138. 
No particular rules with regard to re-drawing processes can 
be given, since the amount of draw or flow of metal required 
depends so much upon the nature of the work that 
is being done. A few examples, however, will enable the 
student to follow what actually takes place during the 
different stages of re-drawing. Fig. 139 gives the complete 
lOwp 



130 



MACHINES FOR SHEET METAL WORK. 



processes for drawing a German silver shell or case for a 
cartridge, particulars of which will be found in Table 1., 




beginning with the blank, and finishing by cutting down or 
trimming the shell. The small metal sphere, fig. 140, is 
made in four processes, including the blank cutting. The 



TOOL DIMENSIONS FOR RE-DRAWING. 



131 



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III 


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loscd to spher 
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Extension, 
id process. 


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S S ? : 1 : 8 


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metal for 
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diameter by 
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211 


Thickness of 
blank 


iiiiiiiii! 

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1 1 1 1 ii-i s i 




Blank 1-281 ''in. 
045 thick 


iiiij 



132 



MACHINES FOR SHEET METAL WORK. 



first process, A, will be cutting and cupping the blank in 
combination tools ; the second process, B, is a re-drawing 
process, or extending the previously cupped blank ; the 



a. a 




FIG. 139. 





mmm m 




third process, C, is to part close the open end of the shell ; 
and in the fourth process the shell is worked into a sphere 
by means of a special punch and die, which may be either 



DRAWING A METAL SPHERE. 



133 





, 






J 




134 MACHINES FOR SHEET METAL WORK. 

called balling tools or closing tools. Particulars of the 
dimensions at the various stages will be found in Table II. 

Another small shell, fig. 141, is drawn and headed. The 
particulars relating to this example are contained in Table III. 
The particulars that are given in Table IV. relate to the 
processes of drawing a small metal shell, but there is no 
drawing given to this example. 

The complete processes of drawing and heading one form 
of cartridge shell are shown at fig. 142, and a study of 
Table V. will provide all particulars to enable the processes 
to be followed during the various stages. After cupping the 
blank the re-drawing, extending, lengthening, or deepening 
is carried out by a series of successive stages, at the same 
time reducing the diameter of the cup, or which we may now 
call a shell or tube, having one end clostd. The number of 
stages that are necessary for re-drawing or deepening a shell 
will greatly depend upon the condition of the metal when 
being worked. The action of the drawing tools tends to 
harden the metal, thereby making it necessary to anneal the 
article several times during the various stages through 
which the shell passes, to be formed into the long shell. 
The open end of the shell is afterwards reduced or closed by 
special reducing or closing tools. Work of this kind is 
frequently required to be tapeied inside the shell; in other 
words, the metal of the shell to be thinner at the open end 
than near the head. This thinning of the metal will be 
brought about by making the drawing punch slightly taper. 
Then, during the drawing process, the punch being smaller 
in diameter for some distance from the end, will pass the 
shell through the die with comparatively little draw until 
it reaches the larger part or swell on the punch, when a flow 
of the metal will be brought about, resulting in the 
required reduction in thickness of the metal shell. The 
shape, both inside and outside drawn shells, is governed to a 
considerable extent by the shape or form of the drawing 
punch, both for its whole length and the end which enters 
the work for carrying it through the die. By increasing or 
decreasing the radius on the drawing corner of a punch a 
corresponding increase or decrease may be obtained at the 
corner of the article that is being drawn. But a point of 



FORMATION OF CARTRIDGE SHELL. 



135 





i 






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if 


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ak -993 diameter b; 


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wlli 


i diameter by '051 


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lllll 


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liiiSil! 



13G 



MACHINES FOK SHEET METAL WORK. 



3 

14 

i 



I I i i i i 



reduced in 
etcr causing 

< \trll-i"li 






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P 



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? 9 



Thickncw) of metal fo 
blank -12:, in. 



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i I 



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ail 



I * I II JS I 1 1 
1 i ii i il I I 



^ 3 



SUCCESSIVE PIERCING AND BLANKING 



137 



importance to be remembered is that, even when a compara- 
tively sharp corner is required on the work, it is not 
advisable to make the drawing corner of a punch too sharp, 
or it will tend to cut and tear the metal. 




A set of successive piercing and blank cutting tools are 
shown at fig. 143. The wrought-iron holder B is bored out 
at H to receive the piercing punch P, and the cutting- 
out punch P 1 . The distance between these two punches 
centre to centre, is equal to the diameter of the washer 
blank plus the amount of scrap or waste metal necessary 



138 



MACHINES FOR SHEET METAL WORK. 



between each pair of blanks. The metal M is passed 
along to cover the die, when punch P 1 cuts out the 
small blank P B, this makes the hole in the washer and 
may therefore be called the piercing bit P B of the washer. 




Fio. 144. 

The motion of the press next moves the slide carrying the 
punches up to the top of the stroke, whilst the operator or 
feed rolls, as the case may be, move the metal M forward. 
On the next down stroke, the guide peg G finds the hole in 
the centre of the washer which has been pierced on the 
preceding down stroke, and the punch P cuts out the actual 



S 





washer blank W, at the same time the smaller punch P 1 makes 
a hole in the part of the metal from which the next washer blank 
will be cut. At fig. 144, M, the scrap metal is seen as it would 
appear after the press has made two down strokes. A 



STAMPING A STEEL WASHER. 



130 



complete washer ready holed has been cut from W and the 
piercing bit of another washer has been cut from P 1 B 1 in 
the metal scrap. The washer W is seen in plan at fig. 145. 
The stamp die, fig. 146, seen in part section S D, is used for 
stamping the bevel upon the outer edge of the washer and 
rounding the edge of the hole in the washer. This is a point 
of importance as it ensures the washer bedding up well under 
the head of any bolt upon which it may be iised, thereby 
preventing the trouble which might be caused if a sharp 




FIG. 147. 

edge was left on the hole of a washer ; for should a bolt 
happen to be a tight fit, it might be necessary to ease the 
hole by filing. This may seem to some mechanics a small 
point, but it is of importance to remove the frase from the 
hole in the same stamp die that does the beveling on account 
of the cheapness of the method as compared to filing the 
frase from each washer separately. 

The set of tools fig. 147 would be used to produce a 
similar washer ; but these tools would cut and hole the 



140 



MACHINES FOR SHEET METAL WORK. 



washer at one blow. P is the punch, having a shank A to 
fit the hole in the slide. The punch P works over the die 
D and forms cutting edges both inside and outside the die, 




FIG. 148. 



E 1 and E 8 being the cutting edge for the outside diameter 
of the washer blank, the hole being pierced by the cutting 
edges E 3 and E 4 . At the centre part of the punch a ring 
R, R 1 , shown in section, is provided with a spring, acting 



COMBINATION TOOLS. 141 

behind it. This is to force the washer out from the punch. 
Another ring, R 1 , R 1 , shown upon the die, is backed up by 
another spring, so as to raise the scrap metal from the die. 
These extractor rings are sometimes backed up by means of 
an indiarubber ring or washer, which acts as the backing-up 
spring. One form of combination tools is seen at fig. 148. 
These tools are used for cutting out a blank and raising it 
into a thin metal cap E. The edges E 1 and E 2 on the punch 
P cuts out the blank. The punch, in its travel on the down 
stroke, forces the blank down between the walls E 3 and E 4 of 
the die D. Inside the die is an anvil or raising peg A, and 
the tools are set in such a position that when the punch 
reaches the bottom of its stroke the face F of the punch just 
brings sufficient pressure upon the top of the anvil, or 
forming peg, to form the metal cap E. During the operation 
the punch and blank, in the down stroke, will have forced 
down the ring R, R, thereby causing the rubber backing-up 
ring to be compressed. Upon the return stroke of the punch 
this extractor ring R, R will again return to the position 
shown in fig. 148, enabling the cap E to be lifted out of the 
die. The same cap E may be made in a different set of 
tools, fig. 149. In this case the tools are made for a double - 
action press. The lower die D is fastened to the bed of a 
power press, and the combined cutting or blanking punch, 
and blank holder B P, is worked by the outer slide, and 
moves slightly in advance of the drawing punch D P, which 
is actuated by the inner slide. The outer slide of the 
double-action press is so arranged that, after making its 
stroke to cut out the blank, it stops during about one 
quarter of the revolution of the crank-shaft The blank 
having been cut from the sheet metal by the cutting edges 
C, C 1 , it is now passed down and held between the face a, a 1 
of the punch and the face e, e of the inside of the die, during 
the down dwell of the outer slide, whilst the blank is held 
here by a pressure which can be regulated according to the 
requirements of each particular case. The drawing punch 
D P, which is connected to a second or inner slide, continues 
its downward movement, thereby drawing the metal from 
between the pressing surfaces a, a 1 and e, e into the required 
shape. It will be readily understood that in this manner 



142 



MACHINES FOR SHEET METAL WORK. 



the metal is prevented from wrinkling or puckering during 
the drawing or raising process. In this set of tools, fig. 149, 
the face a, a 1 of the blanking punch acts as the pressure 
plate instead of using a special pressure plate to prevent 
the wrinkling or puckering of the metal, besides doing the 
cutting out. The puckering of the metal is more likely to 
occur when drawing thin blanks than with thick ones. 

Many articles that are made or formed into cups from 
thick metal may be so formed without the use of a pressure 
plate, whereas the pressure plate would be essentially 




necessary with the thinner metals. The separate pressure 
plate of a drawing press would generally be used in the 
process of making any article having a flanged top. 

The three sets of combination cutting and cupping tools, 
figs. 150, 151, and 152, are in the position that they would 
have reached, after passing their blanks through the die. 
These and similar tools are worked in a double-action press, 
as tliey cut out and cup the blank at one stroke of the 
press. The sketches give a section through the tools, and 



CONSTRUCTION OF DOUBLE-ACTION PRESS. 



143 



they illustrate the construction of three different ways by 
means of which the punches are attached to their respective 
rams or slides. In tools of this kind it is essential that the 




liThTTil 




two punches be made and fitted perfectly true and in 
alignment to each other to enable good work to result. 

Referring to fig. 150, the cutting punch D P is screwed 
into the inner ram by means of a steel rod, known as a 
" tommy lever," being placed in the hole L for this purpose, 



144 



M \. MINK- r.,|; -IIKK.T Mill A I. U OKK. 



having firmly secured D P to a. The outer or cutting 
punch C P is now passed over the drawing punch, and 
brought up to the bottom face of the outer slide 6. The fact 





Flo. 152. 



of the drawing punch being inside the cutting punch makes 
the tools practically self-setting, as both punches when they 
come together, are in. perfect alignment. The punch C P is 
fixed firmly against the face H of the outer slide b by the 



ATTACHING PCTNCHES IN DOUBLE-ACTION PRESS. 145 

hook-headed holts d, the shank of the bolts passing through 
the hole 0. The face e of the punch C P cuts out the blank 
and pushes the blank into hole e l of the die D 1 . And since the 
ram a is a sliding fit in slide 6, when this slide b comes to rest, 
the face e of punch C P holds the blank in position, whilst 
punch D P forces the blank through the die to form the cup, 
during which process the blank is drawn or dragged from 
the face e by the down stroke of the drawing punch D P. 

At the bottom of the cupping die a small bevel is seen 
at K, this to some extent prevents the chipping that 
frequently takes place at the bottom edge of the die, and 
which is the result of the excessive friction due to the action 
of drawing. This chipping action or breaking away at the 
bottom edge of the die during the process of heavy drawing 
due to the excessive pressure often results in the bursting 
of the die. 

Immediately below fig. 150 will be seen an inverted plan 
of the two punches, H being the face on to which the hook- 
headed bolts come, e the face of the cutting punch, and D P 
the end of the cupping punch. 

Figs. 151 and 152 do not need full explanation, as the 
same lettering is used as in the case of fig. 150. In fig. 151 
the bolts are dispensed with, as the cutting punch is screwed 
into the outer slide, and in fig. 152 the cutting punch C P, 
being turned to just enter the hole in the outer slide, set 
pins are passed down through the flange of the outer slide, 
and screwed into collar H of the punch. In this case the 
cupping punch is pushed up from the bottom of the hole in 
punch C P. Bring the cupping punch into perfect align- 
ment, ready to be fixed by some form of gartering at I. 
To prevent the punch D P dropping down, the garter key 
may be fixed in the ram at W, whilst the slot N allows the 
gartering to be done without removing the inner ram. 

Referring again to the breaking away at the bottom edge 
of a drawing die, this edge must be a sharp corner, since 
this corner is practically all that is to prevent the cup from 
re-entering the die upon the return stroke of the drawing 
punch. This edge has also to act as an extractor or stripper, 
to remove the cup from the drawing punch. When drawing 
cup-shaped articles or re-drawing shells and similar work, 
IlWP 



146 MACHINES FOR SHEET METAL WORK. 









CUPPING DIE 




DRAWING DIE 




Fio. 154 



REMOVING SMALL SHELL FROM DRAWING PUNCH. 147 

after the cup or shell has passed through the die, a 
slight expansion of the metal article takes place at the top 
edge ; this expansion or springing is the result of the 
elasticity of the metal, and, as a rule, expands the top of an 
article sufficient to prevent it being drawn up again through 
the drawing die upon the return stroke of the punch. 

Fig. 153 gives three different styles of finishing the corner 
or bottom edge of the die : A is made perfectly square or a 
right angle ; B has been finished by a round-nosed turning 
tool being brought up against the edge ; and C is finished at 
an angle of 45 degs. with the bottom of the die. This finish 
C is by far the strongest, and gives better all-round results 
in working. 

Fig. 154 shows the difference between an ordinary cupping 
die and a re-drawing die. The cupping die is bored 'or 
recessed at the top to a depth equal to the thickness of the 
blank. The blank is dropped into this recess, and held 
central whilst the cupping punch moves down to its work ; 
or, instead of recessing the cupping die, there may be a 
guide plate fastened to the top of the bolster. In the case 
of the re-drawing die, fig. 154, this die is bored out to receive 
the shell, and is usually recessed to a sufficient depth to 
hold the shell upright and steady whilst the re-drawing 
punch enters the shell to begin the work of re-drawing. 

When re-drawing or extending long shells of small dia- 
meter, it is frequently very difficult to remove the shell from 
the drawing punch. This is particularly so when the metal 
is very thin, there being no strength at the top edge of the 
shell to engage the sharp edge of the die bottom. A good 
method to overcome this difficulty is seen at fig. 155, where 
it will be noticed that special slides are fitted to the bottom 
of the die bolster B, and held in position by a plate, these 
slides being drawn up to the punch by means of small 
springs. Beginning at the left-hand side of the sketch. In 
the first process a punch P is about to begin re-drawing the 
metal shell S, and pass it through the die D. The second 
figure gives the position of the tools after the re-drawing 
has commenced, and the shell has forced the small slides X X 
out of the way. In the third figure the re-drawirig process 
has been completed, when the small slides X X have been 



148 



MACHINES FOR SHEET METAL \V"i;K. 



drawn up to the punch under the action of the springs, and 
the slides X X have, as it were, clipped over the top of the 
long shell. The fourth figure shows that the drawing punch 
has been withdrawn from the die upon the return stroke of 




the press, and the sharp edges of the little slides X X have 
clipped over the shell and up to the punch, and prevented 
the metal shell S from following the punch. 



SELECTION OF A SUITABLE POWER PRESS. 149 

CHAPTER XII. 

PRESSES FOR SPECIAL WORK. 

Definition i. A raising press is generally under- 
stood to refer to a machine th~at has been specially designed 
to be used for raising into some hollow shape a previously 
cut blank. 

Definition 2. A drawing or extending press is a 
machine that is used for making deeper, or extending in 
length, any article that has been previously raised or 
Clipped put of the flat metal, and the length of stroke in an 
extending press is usually much greater than that in an 
ordinary raising press. 

Definition 3. A cutting-out and raising press is 
a machine that cuts out its own blank, and simultaneously 
raises it into some hollow shape, at one operation and at one 
stroke of the press. This machine is also known as a 
cutting and cupping press. 

In workshops where a limited number of machines are 
available for use, one press of an ordinary standard pattern 
is frequently used for an extensive variety of work. This 
often necessitates the use of special fixtures, which have to 
be provided to receive the different sets of tools that are 
required to perform the varied operations. But although a 
strong and well-designed press may at times be used as a 
general purpose machine, it is not always profitable to 
employ one press upon too many varieties of work, since the 
extra cost of providing fixtures, and the risk of breakages, 
that sometimes occur when executing heavy work, will 
frequently out-balance the apparent advantages. There is 
generally some special feature contained in the design of a 
press to make it particularly suitable for carrying out some 
special work or operation ; in other words, the designer of 
any machine has invariably had in view some particular 
operation to be performed by the machine. With the 
assistance of a series of illustrations, it will be interesting to 
note some of these special features as they occur in the 
design of the machine being dealt with, as in this way the 



150 MACHINES FOR SHEET METAL WORK. 

actual part of the machine may be seen. The author has 
known instances where an ordinary cutting-out or blanking 
press has been made, sold, and used for cutting, cupping, 
drawing, raising, and stamping, pimply because the stroke 
of the press happened to be of sufficient length for the work. 
From this it would seem to be difficult for one to be able to 
judge for which operation the machine is most suitable. 
The first thing required is naturally a sample of the work 
to be made in the machine ; having this sample, and 
knowing the operation or number of processes required to 
produce the sample, the next step will be to select a machine 
giving suitable motions and of sufficient strength for the 
work. This selection can generally be made successfully by 
the mechanic who has charge of the section where the 
operation is carried out. But in important cases, doubtless 
the better course to adopt would be to seek the advice of 
the actual press maker, who with his special experience may 
be better able to recommend a machine suitable to the 
requirements. 

The following brief points are generally considered to be 
of importance in selecting any screw or power press : 

No. I. Sufficient weight of metal used in construction 
of the frame casting to give strength and rigidity, and make 
it impossible to spring from its normal shape when dealing 
with the work for which it is intended, and ensure freedom 
from breakdowns. 

No. 2. The part of the press and its strips which 
guide the slide or ram in its motion, should be carefully and 
accurately planed, being finished absolutely at right angles 
to the base, or table of the press, which receives the bolster 
or bottom die. This point is of particular importance 
in the case of a drawing or extending press of long stroke. 

No. 3 The slide or ram to be as long as possible, its 
bearing surfaces and those of its guide strips to be of 
sufficient area, and of suitable shape, to provide a steady 
motion to the tools, thereby preventing the cutting edges of 
cutting or forming tools being damaged after the slide or 
ram has once been properly adjusted. 

No. 4. The press bed, the ram, and the adjacent parts 
to be as heavy as possible consistent with the size of the 



IMPORTANT -POINTS IN PRESS CONSTRUCTION. 151 

press, to enable the principle of the anvil to be successfully 
carried out. Plenty of metal to resist the sudden blows to 
which the press may be subjected, and to reduce vibration 
to a low limit. 

No. 5. The details or smaller working parts, to be 
of sufficient proportions to give the necessary strength, and 
the wearing surfaces should have ample bearing surface, suit- 
able metal being vised for their construction, and hardened 
where necessary, durability of working parts receiving 
proper attention. 

No. 6. There should be ample room on the bed or table 
of the press to receive the various bolsters and dies, the 
ram or any other working parts which have to take variable 
positions to have sufficient length of adjustment. This 
point is of particular importance in the case of the ram, 
unless all bolsters, dies, and punches are designed to one 
standard length, which is not often the case. 

No. 7. The methods of manipulating the press, starting 
and stopping the operating levers and adjustments should 
be designed to give the greatest amount of ease and con- 
venience in working. 

In seeking out the foregoing points endeavour should be 
made to select the machine which, in its general design, is 
of shapely outline. This is often overlooked as being of no 
direct benefit ; even should this be so, the indirect advantages 
are worth obtaining, especially as no addition is necessary to 
the cost. These indirect advantages being, the makers are 
far more likely to take pains and carefully finish the working 
parts of a shapely machine than of an ugly one. The 
operators also have more encouragement to keep the machine 
in good working order hy cleanliness, and usually take 
greater interest in machines that show the improvements 
than they do if the machine is clumsily designed and of 
indifferent finish. 

The fly-press, fig. 156, is a design suitable for a variety of 
work. The slide is of the dovetail section, as was seen at 
fig. 12. This provides a large wearing surface to the slide 
and steadiness for guiding the tools, thereby ensuring to 
them a long life. In fly-presses the slide guide is sometimes 
cast separately, being fixed to the press body casting by a 



152 



MACHINES FOR SHEET METAL \\'<>KK. 



bolt ; this is, however, though common, not good practice. 
In the case of fig. 156, the guide being cast solid to the 
press body makes a much stronger job. The connection 
between the slide and screw is provided with a screw adjust- 
ment that serves to take out all play due to wear, the details 
of which connection are seen at figs. 19 and 22. The extent 
of the slide's descent is regulated by adjusting screws and 




F-o. 15<5. 

stop plate. The stay-bolt seen on the front of the press can 
l>e readily inserted or removed, its object being to make the 
press nearly as strong as if double-sided, in case the press 
should be required to do exceptionally heavy work. It is 
often necessary to execute work under this type of press 
that is too large in area to be placed nnder a double-sided 
press, and it is when this class of work has to be dealt with 
that the stay-bolt would lie removed. 



THE USE OF A STAY BOLT ON A PKESS. 153 

The single-acting cutting-out press, fig. 157, is one known 
by Messrs. Daniel Smith and Co. as the " Gem Series," the 
special feature of this press that has caused it to receive 
such a title being that the body and stand are cast in one 
piece. The connecting rod swings on a ball base, which 
allows of its free rotation on the upper or bearing part of 




the rod. This gives a ready and simple mode of vertical 
slide adjustment, to suit the variable lengths of the tools, or 
the extent to which the punch enters the bed, or the degree 
of pressure that is required to be put upon the work in the 
case of raising or pressing. The stop motion is of the 
annular type, having three engaging slots. The engaging 
key will rotate the press in either direction, and it auto- 
matically disengages when the slide reaches the top of its 
stroke. It will be noticed that in this type of press the fly- 



154 



MACHINES FOK SHEET METAL WORK. 



wheel is supplemented with fast and loose pulleys. This 
saves the bnnd or belt being thrown oft' the driving pulley 
or flywheel when tools are being set, or when the press is in 
any way put to rest. This point is mentioned because it 
frequently happens that small presses of this kind are driven 
from the flywheel, which makes it necessary at times to 
remove the belt altogether from the machine. 




The small single-acting press, fig. 158, would generally be 
useful for small work in any kind of sheet metal, say, for 
instance, blank cutting, up to li in. diameter of 14 B.W.G. 
metal, or its equivalent. The adjustment of slide is made 
by packing plates, a method previously explained (see figs. 
41 and 42). A plate in the front of the slide, being readily 
removable, gives free access to its adjustments. On presses 
of this type a small hand wheel may be fixed upon the shaft 



SINGLE-ACTING POWEK PRESS. 



155 



at the back of the flywheel, to euable the shaft to be moved 
by hand for tool setting purposes. The stop motion is of 
the doable peg type, the peg passing through and being 
supported by the boss of the flywheel. This is a safe and 
handy arrangement, there being no tendency for the shaft 
to rotate when setting tools. The friction lever or handle 
seen on the side of the slide guide serves to retain, by 




friction, the slide in any position of its stroke, while the 
vertical adjustment of the slide is effected to suit the length 
of the tools which are being set When this friction lever 
has not been attached to presses of this single-acting type, 
the author has known instances where experienced tool- 
setters have had the ends of their fingers smashed whilst 
changing the adjusting plates, the trouble being caused 
through the slide falling down, due to its own weight. 



156 



MACHINES FOR SHEET METAL WORK. 



A compact form of geared single-sided press, which takes 
up but little space, is seen at fig. 159. It has a vertical 
adjustment in the slide, being also fitted with a special 
sliding block stop motion, made to work by treadle. This 
stop motion automatically disengages when the slide reaches 
the top of its stroke. 

A single-sided press is shown at fig. 160. In this case it 
has a massive box stand and a back drive, there being a 




friction clutch at the back, inside the two speed cone 
pullies. The clutch gives a ready means of stopping the 
entire press, l>ur;m*e with the two speeds the loose pulley 
cannot l)e used except by the aid of a countershaft. But if 
the top driving cone is fitted on the main shaft, the friction 
clutch, as shown, gives stopping and starting control of the 
^'oariiiLT, whiltf the usual stop motion in the slide is variable 
'for constant use if required when cutting out. This back 
drive is very convenient for dnving the press from a shaft 
overhead. The geared incline press, fig. 161, is suitable for 



GEARED SINGLE SIDED PRESS. 



157 



piercing or holing large washers, axle plates, or raising 
ferrules, or bending articles into shape either in the hot or 
cold state. The press, as illustrated, would cut out a blank 
4 in. diameter by 4 in. thick. The stop motion is arranged 
for hand or foot, and a screw adjustment is fitted to the 
connecting rod. The main casting is in one piece. The front 
stay bolts are removable, and the rate of speed in such a 
press, if piercing axle plates or similar articles, would be 
about 70 revolutions per minute. 




The open-backed press, fig. 162, is designed to be used 
either as incline or upright pattern, single acting or geared, 
as required by circumstances. This is a very handy type of 
press, suitable for users who require to deal with small 
quantities of work having a wide range that is, light, 
medium, and heavy. A belt put on the wheel, seen at the 
right of the illustration, will work the press as a single-acting 
one, suitable for light sheet pressings or raisings, such, for 
instance, as can bottoms and tops, tin boxes, and similar 
articles; or, by sliding the pinion on the back shaft into 
gear and putting a belt on to the pullies, seen at the left of 



158 



MACHINES FOR SHEET METAL WORK. 



the illustration, the press at once becomes a geared one, 
available for such work as electric-light fittings, bending and 
forming, cutting out, lock 'plates, spoons, since the use of 
the gearing gives a slower speed and greater power to the 
slide, thereby enabling much thicker metal to be cut. The 
slower speed is often a great convenience, as it admits of a 
continuous feed, without the constant use of the stop motion, 




as is often the case on some kinds of work. The open back 
is available for the work to fall through when the press is 
being used as an inclined press. Fig. 162 shows the press 
placed in position, ready to be used as an upright one. By 
loosing the bolts which pass through the semi-circular base 
of the press, the body can be tilted to a suitable angle, 
thereby converting the press into an inclined one. The 
press stands on heavy cast-iron legs. 



CHIEF DEFECTS IX SINGLE- ACTING PKESS. 



159 



A type of press called single-acting is shown at fig. 163, 
this pattern being used extensively. Its chief defect is the 
form of stop motion, that tends to stop the motion of the 
slide the moment the operator's foot is taken off the treadle. 
This is sometimes with the slide up at, or near the top of 
its stroke, and at others with it down at, or near the 
bottom ; and it frequently requires some considerable 




practice] on the part of the operator to get into the way of 
stopping the slide in the right place. Even when this 
type of press is operated by a competent attendant, it is 
subjected to the great knocking and hammering at the 
clutch, as was mentioned when figs. 43 and 44 were being 
described. This defect is, however, overcome by the 
substitution of the special stop motion, described and illus- 
trated at fig. 172, which disengages and leaves the slide at 
the top of its stroke, and avoids the unpleasant shock. It 



160 MACHINES FOR SHEET METAL WORK 

is also much easier to work the treadle than wlu-n tin- 
ordinary clutch is used, as with the special stop motion, 
fig. 172, there is little or no shock to the foot of the 
operator ; whereas, with the claw-clutch stop motion, the 
operator feels an unpleasant jerk or shock each time the 
press is started 

The single-acting press has its chief application in light 
work, or that of medium strength, say up to 14 B.W.G. in 
iron or steel, and to about 10 B.W.G. in brass, and even 
thicker in copper. But when any of these metals exceed the 
thicknesses here mentioned, then a geared press is to be 
preferred, for the reason that more time is allowed to do 
the actual cutting, and the press is saved those sudden 
jerky strains that so frequently break the main casting or 
the end of the crank shaft. In the steel trades the number 
of breakdowns that arise from this one cause is notorious, 
especially when cutting thick steel, and it is of a hard 
nature, and sheared cold ; whereas a geared press of the 
same strength would do the same, if not heavier and harder 
work, with less strain, all because the work is done 
gradually, and therefore with less shock. 

In the case of heavy work in single-acting presses at a 
high velocity, the almost instantaneous manner by which it 
dashes the tool through the metal, or forces out the blank, 
is liable to break the main casting or shaft ; and one of the 
functions of gearing should be the avoidance of this sudden 
imposition of great strain on the main casting. For cutting 
out hot work, or for bending, squeezing, and forging, the 
gearing is not so important, so long as the thickness is not 
too great. All forging and squeezing should be done as 
rapidly as possible, as in the Ryder forging machine, for 
which the single-acting press is a cheap substitute. 

The single-acting open-back upright press, shown at fig. 
164, is of the long-slide series, having long slides and 
guides. It is, therefore, best suited to work requiring a 
long stroke. The connecting rod has screw adjustment, 
and at the base of the rod there is a wedge adjustment to 
take up future wear. There is a loose gland or cap on the 
base of the slide, handy for the ready removal of the punch 
or top tool, without removing or even disturbing the 



SINGLE-ACTING OPEN-BACK PRESS. 161 

bottom tool or die. The many advantages of this arrange- 
ment will be apparent to those who have had experience in 
press-tool setting. Fig. 164 also shows a loose bedplate, 
that can be removed or replaced with others of various 
thicknesses or styles to meet great ranges or varieties of 
work. It will also be seen that a rod is placed in one of 




Fio. 164. 

the holes of the bottom nut of the connecting-rod adjust- 
ment, ready to raise or lower the slide. A press of similar 
construction is shown at fig. 165, with the exception that 
this press is geared with helical wheel and pinion. 

In fig. 165 it will be noticed that a rod is placed in a hole 
of a cast-iron disc. This disc serves the double purpose of 
assisting the tool-setter by enabling him to raise or lower the 
slide by means of the rod, and the disc having one point in 
its circumference standing higher than any other, this high 
12wp 



162 



MACHINES FOR SHEET METAL WORK. 



pomt comes against a piece of hard wood, thereby actin_r us 
:i brake to stop the press bolt or slide when it has reached 
the top of its stroke. 

The cutting-out and raising press, fig. 166, is of an older 
design than fig. 167. In the case of the design, fig. 166, 
there are the usual cams on either side of the crank opera- 
ting on hardened steel rollers carried by crossbars, which 




are secured to the square frame. Over the cams are another 
pair of rollers connected to the upper part of the same frame. 
This gives a positive lift to the pressure plate ; this is of 
importance when the pressure plate is required to carry 
a cutting-out tool that is, to cut out and then immediately 
secure its blank and prevent wrinkles forming whilst the 
forcer punch sends it into the die. The springs shown are 
for the purpose of balancing the pressure-plate framings. 



PRESSURE PLATE WITH POSITIVE LIFT. 



163 



In the case of a drawing press being used for cutting out 
the blank previous to drawing or raising it into some deep- 
formed article, it is much better for the pressure plate to 
have a positive lift, because sometimes the top tool will jam 
or bind in the bed, or the metal may get between and cause 
it to bind, and then the springs by themselves (see fig. 166) 




would not lift it out, on account of the springs not being 
sufficiently powerful. 

There is another form of pressure plate used for drawing 
extra deep work. This type has a nozzle fitting inside the 
die which presses the work against the inside of the die, 
thereby keeping the wrinkles out of the metal whilst the 
drawing process is further continued. In this kind of work 
the positive lift to the pressure plate is very desirable. 

In the case of feed rolls and feed motions being used 
in drawing presses, the positive lift to pressure plate is 



164 



MACHINES FOK SHEET METAL WOUK. 



essential, because the work is usually cut and raised at the 
same time, so that in case the blanking tool was not lifted 
out of the metal, the rolls or feed motion could not work, and 
the resulting derangement would lead to waste of material, 
loss of time, and a necessity for entire re-adjustment 

The press, fig. 167, combines the advantage of a cutting- 
out, raising, and drawing press. The pressure plate descend* 




Fio. 167. 

by gravity until it rests on the lower die, then the 
continued descent of the forcer slide (by means of the central 
rollers) acting upon the incline expands the inverted toggles 
under the adjustable rollers, which are secured on to the 
side of the main frame of the machine. This transfers the 
pressure required to hold down the blank on to the main 
casting, and thereby relieves the crank of this duty, the 
crank having to only sustain the pressure of raising the 
blank. 



ADJUSTING THE PRESSURE PLATE. 



165 



Fig. 168 shows the change in the position of the parts 
when the crank is at the bottom of its stroke. There are 
toggles and adjustable rollers at the back and front of the 
slide, the pressure plate being held down at four points, the 
adjustments are positive, the effect being that the work 
done in this press would be of an exceedingly uniform 
quality. A press of this type, figs. 167 and 168, would be 




specially suitable for such articles us lock-furniture knobs, 
bedstead knobs and mounts, chandelier weights, drinking 
cups, lamp bodies, cones, burners, &c. The pressure plate 
may be removed from the press in a few moments, when the 
press immediately becomes available, either for cutting out 
blanks, drawing, extending, and reducing work (that has 
been previously raised by the aid of the pressure plate). 
This form of press, with the pressure plate removed, is 
shown at fig. 169. In presses of this type the crank and 



166 



MACHINES FOR SHEKi 1 METAL WORK. 



its load should he effectively balanced during descent, ;md 
this can be done by having a disc within the spur wheel, 
which is heaviest on the opposite side to the crank. 

The double-crunk, double-sided geared press, fig. 170, is a 
special design for cutting large blanks for baths, two or 
three thicknesses of metal l>eing cut at one stroke. Such a 
press would l>e about six tons weight, and could pass a 




Fir.. 160. 

blank through its base measuring about 43 in. by 19 in. 
The slide has a vertical adjustment effected by eccentrics 
caused to rotate by a tangent screw projecting in front of 
the slide. This means of adjustment always keeps the l>ase 
of the slide parallel with the bed or table of the press. The 
slide is also balanced, thereby preventing any tendency for 
the slide to overrun in its downward stroke, or unexpected 
falling of the slide due to its great weight. This feature of 



ADVANTAGE OF BALANCED SLIDES. 



107 



balancing the slides secures safety to the operator. The 
double-helical gearing is driven by a friction clutch, which 
is automatically disengaged as the press slide reaches the 
top of its stroke ; pressure on the front treadle allows the 




clutch to engage and thereby stare the machine in motion. 
The speed of a large press, such as fig. 170, is usually about 
30 strokes per minute, and the cutting-out tools would 
have waved cutting edges, giving shear to the tools, thereby 
enabling two or more complete bath bodies to be cut out at 
each stroke of the press. 



1G8 



MACHINES FOE SHEET METAL WORK. 



CHAPTER XIII. 
DOUBLE-ENDED PRESSES. 

THE [advantage of the double-ended type of geared press, 
fig. 171, is that two presses are fixed and worked, occupying 
much less space than would be the case if two single presses 
were -used; further, they come out at much less cost in 
making. When there is a great quantity of repetition work, 
and -not much tool changing required, then double-ended 




presses are, in point of first cost and working space required 
for them, a great advantage. The eccentrics are opposite 
each other, the cranks for working the slides l>eing at 180 
degrees, so that the strain of doing the work never comes on 
both together. The stop motion being in the slide is also 



TOOL CHANGING IN DOUBLE-ENDED PRESS. 



169 



a great advantage, and the slides being under independent 
control each can be stopped and started without interfering 
with the opposite end. Expert tool setters have been known 
to change the tools in one end of the press whilst the other 




end has been working. This has been frequently done in a 
similar press to the illustration, fig. 171, and by which means 
will be explained hereafter. 

i' In presses of this kind for heavy work the slides are made 
of best crucible cast steel. This prevents breakage. In 



170 MACHINES FOR SUKJS.T METAL WORK. 

the case of fig. 171 there is a very ingenious and simple 
addition made to the packing plate adjustment. A top 
compensating screw allows any intermediate thickness of 
plate to be readily inserted, giving a convenience almost equal 
to a screw adjustment, so useful when using tools of variable 
length, and in the case of compressing or bending work. At 
the same time it reserves all the strength and solidity of the 
packing plate form of adjustment This is certainly the 
strongest known method of adjustment, but it is sometimes 
so constructed by some makers as to be incapable of fine 
adjustment. In the example referred to, fig. 171, the 
arrangement gives all the convenience that is desired. 
Further, the screw can be run back and will allow the slide 
to descend the top tool, entering into the bottom tool 
without fear of damage, because if the upper tool should 
catch in the lower tool it only rest* there, indicating the 
movement needed to set the bed. The slides in these 
presses are so adjusted that their own weight causes them to 
descend as the screw is unscrewed, and the friction lever |_ 
is just tightened so that the slide is safely retained at any 
point of the stroke. 

SPECIAL, STOP MOTION. 

The special stop motion used on these heavy presses is of 
a form particularly suitable for heavy work. It consists of 
a sliding block, reduced in the extent of its required motion 
by its surface being split up into divisions and corresponding 
projections, as shown by the following illustrations, figs. 172, 
173, and 174. On referring to fig. 172 it will be noticed 
that when the block is at one end of its stroke the spaces 4, 
5, and 6 in the lower block C are open to receive the 
projections 1, 2, and 3 on the upper box J, and the latter 
moves up and down without giving its motion to the slide 
(see figs. 172 and 173). But when the lower block is 
pushed in the direction of the arrow A, or right hand side of 
the slide, see fig. 174, then the projections on the box come 
on to those of the block, and the slide is thereby caused to 
descend. It will be understood that the more divisions 
there are in each block the less distance the block has to 



STOP MOTION ARRANGED IN RAM. 



171 



travel. This is important, since it reduces the time required 
to advance the block to a minimum, and in accord with the 
brief space of time allowed for it to properly engage. The 
projections are preferably made \/ -shape, as shown by fig. 




175. This greatly increases their sectional area to resist 
crushing and bending, and allows of a greater number of 
divisions, and therefore a less travel to be given to the block. 
This is a very great improvement, since it makes this kind 
of stop motion applicable not only to geared or slow-working 



172 



MACHINES FOR SHEET METAL WORK. 



press slides, but al*o to the slides of quick action presses, 
for the very important reason that in all high-speed presses 
it is desirable that when a stop motion is suddenly thrown 
into action it should be so arranged in relation to the 




moving parts that the motion be given to the least possible 
mass. This avoids the destructive effect of repeated blows 
on the parts composing the stop motion, and preserves a 
silence in the working of the press, which is a very desirable 
point when a large number of presses are working in one 
shop. 



PROPER PLACE TO APPLY THE STOP MOTION. 173 




174 



MACHINES FOR SHEET METAL WORK. 



lu the case of a press having the stop motion in the fly- 
wheel, the latter going at 120 revolutions per minute, each 
time the stop motion engages into the crank shaft there is 
an unpleasant shock caused by the mass of the crank shaft, 
connecting rod, slide, and tools, having all to be thrown 
into instantaneous motion. An example of this type of stop 
motion is seen at fig. 176, where a sliding key is withdrawn 
by the extracting mechanism, operating upon the head of 
the key, as the flywheel is rotating. As the inertia of these 
parts is very great in heavy single-acting presses, it 
is obvious that the proper place to apply the stop 
motion in single-acting presses especially in the medium 
and larger sizes is in the slide of the press, rather than in 
the flywheel. Another patent form of stop motion more 




suitable for a single-acting press is the one shown at fig. 177. 
In this example the block is preferably circular, and a 
slight movement of the lever D is sufficient to start and 
stop the press. This motion may be arranged to be effected 
either by hand or treadle. The author has known a great 
deal of trouble to be caused by the continual hammering 
and knocking of the various types and shapes of claw 



DANGERS OF SLIDING- KEY STOP MOTION. 175 

clutches, often resulting in a very heavy cost for repairs in 
the case of quick running presses, besides frequently 
resulting in an operator loosing a finger, due to the sudden 
starting of a press slide. One form of stop motion referred 
to as being a dangerous method of stopping and starting, is 
that type seen at figs. 43 and 44, ; where a cast-iron clutch 
W C engnges another claw clutch C, sliding along the crank 
shaft. A stop motion such as that described and illustrated, 
figs. 175 and 177 if either one or the other were intro- 
duced into the design of the four large power presses, 
figs. 46, 47, and 48 would allow of each press being 
worked separately with perfect success, and the tools could 
be set in any one press whilst the remaining three presses 
wei'e at work. Soch a stop motion has the following 
commendable advantages, viz. : It is positive in action ; is 
in no way tricky or problematical, being easily understood ; 
and it reduces the possibility of an unexpected descent of 
the slide to a minimum. The slide is of such small weight 
as to be readily balanced, thereby removing the liability of 
the crank and slide to suddenly descend in case it gets 
carried just over the crank shaft dead centre, as frequently 
occurs after the stop-motion key has disengaged in many of 
the American presses. In the case of small and medium 
size presses, the slide guide may be set up against the slide 
itself, sufficiently tight to prevent the slide from falling, 
when the stop motion is thrown out of gear, since the 
friction between the slide and slide guides would hold the 
slide at the top of the stroke, as seen in figs. 172 and 173. 
But for heavy slides it is much preferable to use balance 
weights, thereby removing any necessity of setting up the 
slide guides. In fact, it is safer, and much better practice, 
to work with a balanced slide even with the smaller presses. 
The Ryder forging machine, fig. 178, is used extensively 
for making bolts, joint pins, hurdle and fencing ends, and 
analogous work that require reducing or swaging quickly. 
This machine is made in a somewhat similar form as a power 
press, and may correctly be called a forging press. The 
speed is usually about 700 blows per minute, and the 
multiple slides allow a succession of tools to be used, each 
pair doing their part of the work. The back and front 



176 



MACHINES FOR SHEET MKTAL NVOKK. 



crossbars are used for fixing guides and gauges. The anvil 
of each hammer hag a wedge adjustment that is used to 
determine the finished size of the article that is being forged ; 
adjustment can also be made by the screw and hand wheels 
whilst the machine is in motion, and sometimes they are 
connected to a treadle, which can be operated by the 
workman's foot. This mode of working is [to be preferred 
when the required reduction of the bar is considerable. A 




set of shearing tools are in the slide on the extreme right of 
the machine. A forging machine of this type is very useful 
for forging large quantities of press tools of any particular 
shape or dimensions. This is readily carried out by fixing 
suitable swaging and forging tools into the various slides of 
the machine. The metal shearing attachment, fig. 179, con- 
sists of a pair of 12 in. shear blades mounted in a light cast- 
iron holder, having the necessary adjusting gauges affixed. 
These may be readily added to any power press, thereby 
transforming the press into a cross-blade shearing machine. 
This fixture is very handy when material has to be cut up 
occasionally, and it may be made in all sizes to correspond 
with each size or type of power press. 



DETAILS OF METAL SHEARING MACHINES. 



177 



The single-acting guillotine shears, fig. 180, are specially 
suitable for quickly catting iron or sheet metal into squares 
or strips; the stop-motion automatically disengages with 




the top blade, open ready for the insertion of the sheet. Its 
cutting speed is about ninety cuts per minute, if the treadle 
is held down continuously. The machine, as illustrated; at 




fig. 180, would cut sheets 48 in. wide by in. thick. lu the 
front table graduated rules are set for indicating the position 
13 WP 



178 



MACHINES FOR SHEET METAL WORK. 



of the front parallel gau^e to cut any given size of sheet, 
und the back gauge has a parallel motion, also a taper 
adjustment for cutting off taper strips, if required. The 
connecting rods for working the upper blade arm are coupled 
to the blade by being engaged into recesses near the top of 
the upper blade arm, the other end of the connecting rods 
are attached to the crank stiaft. This method of coupling 
to the top blade arm allows a much longer rod to be used 
than is usually seen on this kind of machine, and also avoids 
the tensi >n coming upon a narrow section of cast iron, which 




Fio. 181. 

is very liable to break, as is often the case when the 
connecting rods are coupled near the bottom of the blade 
arm. 

Fig. 181 represents a set of flattening or plate bending 
rolls, for dealing with large safe or bank doors, and similar 
work. After the plate has passed between the rolls, the 
motion of the top roll serves to carry it back ready to be 
put through again. The plate is first bent one way then 
the other. This process removes all indents, surface dis- 
tortions, and unequal tensions, and by the adjustment of the 
parallel motion the plate can be either bent or flattened as 



SHEARING MACHINE FOR CIRCULAR BLANKS. 



179 



required. The parallel motion for providing a uniform 
adjustment is very essential if good and expeditious work 
is required. 

A set of circular cutting shears, used for shearing or 
cutting large blanks, are shown at fig. 182. In this 
example the cutters are started by a clutch motion, operated 
by foot. This allows the cutters to remain at rest whilst 
the sheet is adjusted, without any risk either to the 
operator or of spoiling the blank. The cutters are made 
with double cutting edges, and are accurately ground and 
hardened so that when one pair of edges have become dulled 




by continual wear, they can be reversed, the unused edges 
being brought into action. The lever grip for gripping the 
metal sheet acts instantaneously, and this method is prefer- 
able to the old screw type of adjustment. A graduated 
steel rule is fitted in the bed, so that the diameter of the 
blank to be cut can be readily determined, the adjustment 
of the rule being needed from time to time as the cutters 
are re-ground and the plane of either cutting edges are 
removed in relation to the zero on the graduated rule. The 
horseshoe grip is readily moved along the bed by rack and 
pinion motion, and the cutting head gauges so useful for 
metal splitting operations, can be affixed when desired. 



180 MACHINES FOE SHEET METAL WOltK. 

SHEAR OF CUTTING-OUT TOOLS. 

The shear method of cutting out is usually adopted in 
the case of large blanking tools, to allow of a large blank 
being cut with comparatively little power required for the 
operation, and to reduce the stress on both the tools and 
machine. 

The shear method is carried out successfully when the 
tool which comes in contact with the usuable material is 
kept quite flat, and the shear put upon the tool that will 
distort the scrap only. For instance (1), suppose 
ventilator grid blanks are being cut out, these blanks 
would be required perfectly flat. In this case the punch 
face should be kept perfectly flat, so as to keep the part of 
the metal flat which is required to be used up for the blank. 
The shear in this case will be arranged in the cutting edge 
of the lower tool bed or die, by making it concave or with 
curved cutting edge, and this would distort the scrap only, 
leaving the metal ventilator grid blank perfectly flat. 

2. Suppose ventilator plates are being perforated. This is 
an instance where the order of things must be reversed. 
The lower tool face, or face of cutting bed, should be kept 
quite flat, whilst the shear can be arranged upon the cutting 
edge of the punch, either by making the face of the punch 
concave or convex ; or, if a Dumber of punches are working 
together, they may be made of variable length, so as to 
extend the time during which the actual cutting or piercing 
operations take place. The pieces that are cut out in 
perforating the plate will be scrap, whilst the ventilator 
plate itself will be quite flat, owing to the bottom tool or die 
being perfectly flat It is of no consequence if the scrap 
blanks, scrap piercings, or scrap metal surrounding any 
blank becomes bent or distorted, as they fall from the 
cutting tools ; whilst the ease and comparative silence in 
which the work is done is quite a pleasure, as contrasted 
with the constant repetition of reports incidental to cutting 
when both the punch and bed are flat and without shear or 
curved edges. Referiug to figs. 172, 173, and 174, it will be 
noticed that the pair of cutting-out tools fixed in the press 
are for cutting out round blanks. The bottom tool or die 



CUTTING BLANKS BY THE SHEARING METHOD. 181 

being arranged to shear the blank from these tools will 
therefore be quite flat, whilst the scrap metal will be 
distorted or curved as it falls from the tools of the press. 




Figs. 183 and 184 illustrate a pair of tools for cutting blanks 
of irregular shape and a pair of round blanking tools respect- 




ively. In each case the shear is arranged on the cutting- 
edge of the bed or bottom tool, so that the blanks when cut 
shall be flat. 



182 



MACHINES FOR 8BEET MKTAL WORK. 



CHAPTER XIV. 
ROLLER AXD DIAL-FEED MOTIONS. 

THE principal reason why the roller-f^ed finds more favour 
and is so frequently adopted by sheet metal workers in 
preference to other feeding devices is on account of it being 
the only type of feed that can deal satisfactorily with sheet 




metals of the thinner gauges. Such metals, when being 
handled or uncoiled by an operator, will buckle or break 
unless reasonable care is used in the handling. Further, the 
least obstacle will result in impeding its advancement, and 
care is necessary in dealing with a metal so delicate to 



ADVANTAGES OF THE ROLLER-FEED MOTION. 183 

manipulate. From this it follows that when a roller-feed is 
used the pressure of the rolls, with their length extending 
beyond the full width of the sheet, keeps the latter flat for 
a considerable distance before and behind the rolls ; they 
also tend to keep the metal stiff by giving it additional 
support. The first essential of a good roller-feed is the 
uniformity of its intermittent progressive motion. When 
this is perfect, pierrin<jr and blanking can be done with 
precision at an exceedingly high rate of feed, two hundred 
to three hundred blanks per minute being a very common 
speed for small articles. It is only when a large quantity of 
any particular article is required that the roller-feed is 
adopted. For small lots it has little or no economical 
application on account of the time occupied by an operator 
in adjusting the tools with the feed roll". But when a 50 or 
60 feet coil of metal can be started and cut up entirely, and 
while this is being done the attendant can be fixing up 
a second coil in an adjacent press, it will be readily under- 
stood that the rate of production is greatly increased, and 
the cost considerably reduced. 

As a rule, feed-rotls (especially if they are double) will be 
in the way when tools are being re-set. It is therefore 
desirable that their construction be such as to make it 
possible for them to be readily removed for the purpose 
of tool-setting. This is effectively accomplished in the 
arrangement of the roller-feed, as shown in fig. 185, in 
which the feed rollers are hinged out of the way, the bed 
of the press being quite clear for setting the tools. The 
advantage in vising a double set of feed-rollers is that whilst 
the front pair advance the sheet over the tools, the second 
pair serve to take the scrap or perforated sheet away and to 
deliver the last remnant of the sheet between the tools. 
Another important feature is that both pairs of feed-rollers 
should be capable of simultaneous opening, so that the 
metal sheet between them can be readily liberated and 
adjusted in relation to the tools and their gauges. This is 
accomplished by means of an eccentric lifter, thereby saving 
time. 

The gear should be accurate machine-cut, and the crank- 
pin used to give motion to the rollers should be provided 



184 



MACHINES FOE SHEET METAL WORK. 



with a fine screw adjustment, so that the correct amount 
of advance can l>e given to the rolls. There is also usually 
added a device for automatically coiling up the scrap strip 
as it comes from the press. Small presses of this kind are 
especially suitable for making the covers of safety pin, 
glove fasteners, buttons, stud coverings, chain-links, small 
cups, and other similar small articles, of which a number 




may go together and be assembled to build up larger articles. 
In brief, it may be noted that for thin sheet-metal there is 
no feed-motion which gives better general results than the 
roller-feed motion when properly constructed. For thicker 
metals that will stand some degree of thrust without ready 
deflection, particularly if in narrow strips, the device known 
as the grip-feed, or monkey-feed, claims its place, whilst witli 
wider metal the greater the claim of the roller-feed. 



CONSTRUCTION OF DIAL-FEED MOTION. 



185 



The purpose of the dial-feed motion is twofold. Firstly, 
and most important, it is a device that reduces the risk to a 
minim im of feeding or the laying under of the work. The 
great number of accidents in the way of operators' fingers 




being continually mutilated, would be materially reduced, if 
not altogether avoided, were the dial and other feed-motions 
more generally adopted. The second advantage is that the 
operator can feed the work at an exceedingly quick rate. The 
chief drawback to the use of the dial-feed motion is its cost, 
especially when applied to smaU quantities of work. 
Fig. 186 shows the dial-feed motion fitted to a power press. 



18C 



MACHINES FOll SHEET METAL WORK. 



The function of the dial-feed is to transfer the work from 
the hand that feeds it, into the tools that are used to pierce, 
bend, or reduce the article. Dial-feed motions are made in 
various forms ; the one shown at figs. 187 to 191, is arranged 
for cupping-blanks that have been previously cut out on 
another machine. It usually consists of two circular plates 
about 12 in. diameter, the top plate T P having any number 
of holes an equal distance apart ; the under plate B P is a 
fixture and has one hole only, this being exactly over that in 
the lower tool bed or die; this second or bottom plate BP 
forms a bottom or lower portion to all the holes in the top- 




plate, see fig. 189. The t'-p plate TP is caused to rotate 
intermitently in one direction by a crank motion, usually on 
the end of the main shaft of the press, fig. 188, where it is 
shown in side elevation. A section of the crank motion 
showing the screw adjustment is also given at fig. 186. The 
advance of the plate T P occurs only during the upper half of 
the ascent and descent of the punch and during the lower half 
the upper plate holds the work to be cupped, drawn, or 
pierced, over the lower tool bed or die, while the punch 
descends and does its work. As the crank disc C D rotates, 
it gives motion to the connecting rod CR, which in turn 



DETAILS OF DIAL-FEED MOTION. 



187 



transmits motion through the bell-crank lever B C L to the 
feeding-rod F R. On the rod is fixed a pawl P 1 , and this pawl 
moves the top dial-plate forward in its revolution, the small 
spring S keeps the pawl pressed up against the notches in 
the dial-plate. The function of the locking pawl L P, fig. 190, 
is to keep the top dial-plate steady in position. The blanks 




are placed in the cast-iron tray and pushed forward into 
that hole nearest the centre of the tray each time the 
dial-plate comes to rest they are then carried towards the 
tools as the dial-plate travels round in its revolution. By 
this arrangement the hands of the operator never need go 
near the tools. A rear elevation of the locking pawl is seen 
at fig. 191. The usual speed of the machine is from 100 to 
130 revolutions per minute. Fisf. 186, is the kind of press 
generally employed for making brass balls, knobs, cups, 



188 MACHINES FOR SHEET METAL WORK. 

boxes, lamp burners, cartridge cases, and for accurately 
piercing any kind of blanks. The smaller the size of the 
work, the greater is the speed desirable, and in consequence 
the greater the risk to the fingers of the operator. 

It is possible to adapt one dial-plate to a variety of work 
by making the holes in the plate slightly larger than the 
largest sized article to be dealt with, then fixing bushes 
into each hole of the dial-plate, of suitable shape to receive 
the articles to be pierced, bent, or cupped, as the case may 
l>e. It is, however, much cheaper and less trouble to the 
operator to have a separate top dial-plate for each size and 
shaped article to be handled, for since the complete dial-feed 
motion is already attached to the machine, the only renewals 




required for dealing with new shaped blanks would be addi- 
tional dial-plates. If all the blanks passing through the 
machine are round blanks, and of many different sizes, it 
may be advisable to use bushes in the dial-plates for the 
smaller sizes, since bushes for round work can be made 
considerably cheaper than for irregular shaped articles. It 
is necessary to have the holes in the dial-plates slightly 
larger than the diameter of the blank to be pierced, so as to 
allow for expansion, otherwise the blanks might stick in the 
holes instead of being drawn out by the punch and cause 
trouble or breakage of tools. If the holes in dial-plate are 
made sufficiently large the punch will then lift the blank 
from the hole in the dial-plate, and it will then he drawn oft 
the punch by means of a releaser or stripper. In this case 
it is essential for the press to be inclined, to allow the work 



IMPORTANT POINTS CONCERNING THE DIAL PLATE. 189 




190 MACHINES FOR SHEET METAL WORK. 



J! 




Fio. IPS. 



APPLICATION OF ROLLER-FEED MOTIONS. 191 

to fall from between the releaser and dial-plate, the blank 
dropping into a box at the back of the press. When the 
dial-leed is used for cupping or re-drawing it is also advisable 
to make the holes sufficiently large in the dial-plate to allow 
the blank or cup (as the case may be) to fall freely into 
position on to the die, ready to receive the cupping or re- 
drawing punch. 

The adjustable double action power press, fig. 192, is fitted 
with a set of automatic feed-rollers. This machine is largely 
used in the manufacturing of bedstead knobs and similar 
light brass work. It is fitted with treadle clutch motion, 
enabling the operator to stop the machine instantly if re- 
quired, and, being an adjustable machine, it can be worked 
on the upright or incline position, which is of considerable 
advantage. Since the machine can be worked up to 125 
strokes per minute, and both cuts out the blank and forms 
the shell to shape at each descent of the ram, it follows that 
the output is large and the cost of manufacture reduced to a 
minimum. 

A double-action press of somewhat different design is 
shown at fig. 193. This machine is designed for the same 
purpose as the previous one, but is fitted with a double set 
of automatic feed-rolls for more accurately passing on the 
sheets and reducing the amount of scrap to a minimum. This 
method of working the feed-rolls is a substantial one, the 
arm that actuates the rollers being manipulated by a sepa- 
rate slide from the crank shaft end. For operations which 
do not entail the necessity of these feed-rollers an arrange- 
ment is provided on the bed of the machine by means of 
which the rollers can be swivelled out of the way of the 
operator. 

A power press of strong design is seen at fig. 194, fitted 
with feed-rolls for use when cutting out round or irregular 
shaped blanks from strips of sheet metal drawn automatically 
through the rolls. The rolls may at any time be readily 
removed, and the press made available for general cutting 
out and shallow drawing. The machine is fitted with patent 
positive stop action or clutch, as desired. 

The machine, fig. 195, is an adjustable power-press of 
simple, strong, and serviceable design, and is used extensively 



192 



MACHINES FOK SHEET METAL WORK. 



in the manufacture of sheet-metal ware for working the dies 
in cutting and stamping covers and bottoms of a canister at 




cue operation, and also for cutting body-blai>ks,[piercing, 
embossing, and similar purposes. It is fitted with a treadle 
clutch motion of novel des'gn. An additional attachment 



ACCIDENTS TO OPERATOKS FINGERS. 



193 



known as a finger guard is frequently added to this class of 
machine, and it is claimed that whilst practically prevent- 




Fio. 195. 

ing accidents to the operators' fingers, it also serves the 
purpose of stripping the tin off the top punch. The clutch 
14wp 



194 MACHINES FOR SHEET METAL WORK. 





UNEXPECTED DESCENT OF THE RAM. 



195 



motion arrangement can be clearly seen in figs. 196 to 198. 
We may repeat that the chief cause of the loss of limbs in 
working a power-press is the unexpected second descent of 
the ram when it is not intended or expected. Many 
types of clutch motions are unreliable and accidents will 
occur with them, even if the greatest care is exercised. The 
safety-clutch, however, represented in figs. 196 to 198 
appears to offer advantages worthy of notice. The following 




SIDE VIEW 



explanation will enable its action to be readily understood : 
When the treadle-rod is depressed the " knock-off" C, is 
thrown into an angular position, releasing the clutch and 
causing the ram to make a down stroke. Before the crank 
has completed its revolution the small roller A strikes the 
piston B, releasing the "knock-off" C from the treadle-rod 
The "knock-off" is then instantly thrown back to its original 
upright position (by means of a compression spring) i^i 
ample time to prevent a second descent of the ram. 

Referring to fig. 195, it will be noticed that the ram is 
coupled to the crank shaft in a manner which enables lengthy 



196 



MACHINES FOR SHEET METAL WORK. 



adjustments to be made. A sectional view is seen at 
fig. 199, which explains itself. Another useful design of 
connecting-rod, shown at fig. 200, is suitable for presses in 
which it is desired to bring the ram as close up to the crunk 





Fio. 199. Fio. 200. 

shaft as possible, as is the case with small presses of simple 
design, the adjusting-rod is coupled to the mm by a ball 
joint, and when this is carefully fitted, it is a great success 
und works with very little friction. In some designs the 
screw instead of having a lock nut as shown, is secured by a 
et pin screwed into the side of the strap rod against a 
suitable packing-bit, arranged to firmly hold the screw in 
position without damaging its thread. 



WORM ADJUSTMENT FOR THE RAM. 



197 



ADJUSTING DOUBLE-CRANK PRESSES. 

A difficulty often experienced with double-crank presses, 
is the adjustment of the two connecting-rods, so as to ensure 




198 MACHINES FOR SHEET METAL WORK. 




TOGGLE DRAWING PKESS. 



199 



that the punch or top die (as the case may be) will come 
down on to the bottom die and be perfectly level. This is 




Fio. 203. 

very important when a press has to be used on a variety 
of work requiring connecting-rod adjustments. A r 



A 



200 MACHINES FOR SHKET METAL WORK. 

adjustment is used in connection with some double- 
crank power-presses, and has the advantage that it enables 
the adjusting links to be securely locked at the top and 
bottom. In many makes of presses, particularly those of 
American design, there is no proper means of locking these 
adjusting links or couplings, and the adjustment is therefore 
liable to be altered during the working of the press. 
One tpye of worm adjustment is seen at fig. 201, fitted to 
a cutting-out, stamping, and embossing press, capable of 
exerting a working pressure on the dies up to 100 tons. 

There are instances, where a small adjustment only is 
necessary to meet the slight variation in setting the tools ; such 
a press as is shown in fig. 202, where a pair of wheels are 
attached, one of which is provided with an eccentric brass- 
bush, and by this means an adjustment of 1 in. is provided. 
Such a machine is suitable for cutting out heavy blanks in 
sheet iron and steel for armature discs, blanks for bottoms 
of buckets, baths, and similar work, and is fitted with a 
treadle motion, by means of which the ram makes one 
descent and stops automatically at the highest point. 

A geared press of somewhat similar design is usually 
employed for such work as pannelling or embossing trunk 
bodies and covers, by means of dies, a class of work that has 
usually been done by means of a hand-swaging machine with 
rollers. 

A geared machine known as a togsle drawing press is 
shown at fig. 203 with its slides up. This tpye of press is 
employed upon all kinds of seamless articles, such as basins 
and other kitchen utensils. The special toggle movement 
is provided for application to the blank holder, and by this 
mechanism the pressure put upon the blank under operation 
is borne by the framework of the machine, thereby reducing 
the strain and friction upon the crank shaft. 

A perforating michine suitable for dealing with heavy 
sheets and fitted up with automatic feed-table to ensure 
accurate work is also made. The machine may be em- 
ployed for punching heavy blanks from the sheet, and which, 
owing to the machine being automatic, enables the work 
to be done rapidly and permits one operator attending to 
two or three machines. It is fitted with hand-lever clutch, 



ARMA.TURE DISC-NOTCHING MACHINE. 



201 




202 



MACHINES FOR SHEET METAL WORK. 

by which means the operator can stop the machine 
instantly if required. 




The armature disc-notching machine, fig. 204, is a type of 
machine specially built for the electrical trades. It will be 



FEEDING BLANKS B5T VERTICAL HOPPER. 203 

noticed that the machine consists of an ordinary cutting press, 
fitted to a suitable bed casting which is truly planed to receive 
the powerful automatic and adjustable stop mechanism 
which controls ihe action of the horizontal rotating move- 
ments, ensuring thereby uniformity in the discs that are 
notched in the press. A positive clutch is provided by 
means of which punching is automatically stopped after one 
complete revolution of the disc under operation. 

In some instances, as in the case of chamfering, marking, 
piercing, and burnishing cycle chain links, and similar 
blanks, it is convenient to pass the blanks on to the tools 
automatically. Fig. 205 shows a press fitted up for this 
purpose. Vertical hoppers or tubes of suitable size are 
provided to receive the blanks, and from these tubes the 
blanks are automatically conveyed to the dies to be cham- 
fered, marked, or pierced, and after being operated upon fall 
through the bed into a box placed for their reception. 



204 MACHINES FOU SHEET METAL WORK. 



CHAPTER XV, 
STAMPING. 

THE ordinary stamp, consisting of an anvil, two guide rods, 
pulley, and a hammer that is worked by means of a band or 
rope upon the principle of the falling weight, is a very 
useful arrangement, and is used extensively for raising and 
stamping sheet metals on account of simplicity of con- 
struction and cheapness, when strength is required rather 
than accuracy. Different opinions are held by users as to 
the classes of work upon which this machine should be 
employed, and there seems to be good reason, judging from 
recent results, for stating that it is frequently better to 
employ a strong machine, in the form of a power stamping 
press, that is worked by a crank shaft. This point must, 
however, be settled according to the class of work to be 
done. There are many varieties of stamped goods, and 
necessarily a large number of special stamps and stamping 
machines, many of which are worked upon the principle of 
the falling weight, some of the newer types are worked by 
cranks and cams. 

The case of producing an ordinary washing basin, say, 
16 in. diameter and 5 in. deep, is an instance where a 
number of "forcff," or top dies, would be required if the 
basin is made in the drop stamp. These " forces " will be of 
different shapes, varying according to the number of stages 
through which the article passes before reaching the final 
stage. Each "force" may require two or more blows upon 
the work, according to the actual shape of the article, in 
addition to which the basin will require annealing at the 
various stages to prevent splitting or cracking, since in 
stamping processes every blow of the top die, or "force," 
hardens the metal, frequently causing the article to split or 
burst. In many esses a suitable and powerful raising press 
will raise the article at one blow, thereby saving l>oth time 
and labour. On the other hand, there are classes of work done 



WEIGHT OF STAMP BLOCK AND HAMMER. 



205 



successfully under a drop stamp that could not possibly be 
done economically under a stamping or raising press. From 
this it will be readily understood that the selection of a 
machine to do some particular work will frequently require 
the opinion of an expert. 

The ordinary drop stamp, fig. 206, is generally used for 
hot stamping or drop forgings. The iron in the block 
should be dense and tough. The practice of having them 
cast direct from the blast furnace, thoiigh cheap, does not 





give good results, as the face is too soft to withstand the 
effect of the hammer continually falling on to the lower die. 
Forged steel hammers are to be preferred to steel castings. 
The heavier the block is over that of the hammer the more 
effective is the latter. A good ratio is 12 to 1, and for steel 
drop forgings it should be 14 or 15 to 1. Stamps in which 



20G MACHINES FOE SIIEKT MKTAL WORK. 

soft metal "forcers " are used, a ratio as low as 8 to 1 may 
be adopted. The stamp block should have a large and well 
proportioned flange and a level base. The supposed economic 
practice of having these cast in open sand is not a good 
practice. A level block base can be bedded more solid upon 
its foundations than an uneven one. 

The advantage of the type of double-stamp, fig. 207, is its 
usefulness for light or small drop forgings of irregular shape 
and thicknesses, in which the bar of iron or steel needs some 
preparation to mould it to suit the form of the finished die. 
The first, or the stamp on the left, is fitted with forging 
tools that serve to rough shape, that is, to elongate or thin 
down the bar in one part, while its adjacent part is required 
the full thickness. This is necessary for economising the 
raw material and reducing the superfluous metal to a 
minimum. In this double-stamp the first hammer is called 
the doily, and the second the finisher. It is found in practice, 
when making steel stampings, that both hammers cannot be 
used for finishing, as the concussion and rebound of the one 
hammer tends to the up-setting and loosening of the dies 
under the next hammer ; but this is not so important when 
one hammer only is used for finishing and the other used 
for rough-shaping the material, because the dolly tools are 
comparatively unimportant in their setting, and the more 
solid blows are made by the finishing stamp. These latter 
can receive careful attention to keep them truly and firmly 
set When used iu this manner the double-stamp economises 
space, heat, and time iu the transfer of the work from the 
first to the second stamp. 

The drop stamp, fig. 208. is the ordinary type raised by 
pulley and belt. This kind of stamp is worked either by 
hand or foot. When the work is light, the usual method is 
to connect a rope or strap to reach the operator's foot ; this 
leaves the hands free to place the work upon the lower 
stamp die, the blow being made by the falling of tlie 
hammer each time the operator raises his foot. In heavier 
work the hammer is raised by the hand, then allowed to 
fall, and whilst the operator places the work upon the die 
the hammer is held by the catch, as seen on the left of 
fig. 208. The number of accidents that have happened by 



208 MACHINES FOR SHEET METAL WORK. 

stamp operators having their fingers mutilated has led to the 
introduction of automatic drop hammers. The object of an 
automatic stamp, or drop-hammer, is to raise the hammer 
to the required height, then allow it to fall without the 
attendant pulling or releasing a rope or strap which is 
connected to the hammer. 




Diagram 



The following description of such a stamp, in conjunction 
with diagrams 1 and 2, will enable the operations to be 
understood. Referring to diagrams 1 and 2, on the back 
of the block a projecting bracket is bolted. This serves the 



AUTOMATIC DROP-HAMMERS. 



209 



purpose of carrying the lifting mechanism, which consists of 
a crank motion, rotated by a spur wheel and pinion driven 
by a pulley. The frame extends upwards, and carries in 
suitable bearings a spindle free to rotate, upon which is 
secured a pulley, to which is attached one end of a band 
of leather, steel, metallic chain, or other more suitable 




Diagram 2. 

material ; the other or fall end of such band is connected to 
the hammer. Secured on the outer end of the top spindle 
is another pulley of about one-half the diameter of the 
hammer pulley, and to this pulley is connected another 
band, the fall end of which is connected, through the 
15wp 



210 MACHINES FOR SHEET METAL AVORK. 

medium of a U-shaped lever, to the stud pin in the adjust- 
able crank previously referred to. The relation between 
the connection of the band on the hammer pulley and the 
connections of the band on the crank pulley are such that 
as the hammer rests on the die the band on the crank pulley 
is coiled up, so that any motion of the crank uncoils one 
band and coils up the other. The hammer is thereby raised 
to such an extent as there is disproportion between the two 
pulleys that is, the stroke of, say, a 12 in. throw crank 
would by these means cause the hammer to be raised a 
distance of 4 ft., if the ratio between the crank and hammer 
pulleys were 2 to 1. Any shortening of the crank throw 
would result in a magnified shortening of the distance the 
hammer would be raised, and vice versd. 

Fig. 1, diagram 1, is a side elevation of such a stamp. 
Fig. 2 is a front elevation, with one of the standards S 
removed to show the lifting gear in section, and the other 
part sectioned on line e, f to show detail of screw 28 for 
adjusting the guide or standard S. Fig. 3, diagram 2, is a 
rack modification for lifting heavy hammers. Fig. 4 is a 
plan of fig. 3, and fig. 5 is a section through the line G N of 
figs. 2 and 6 in direction of arrow h. Fig. 6 is a sectional 
elevation through the line c, d of figs. 1 and 5. 

In figs. 1 and 2, B is the anvil block, 8 is one of the 
standards, D is one of the two brackets bolted to the back 
of the block B, C C are two upright back standards resting 
on the brackets D. The standards S are secured to the 
block B by bolts m, and slot holes allowing the guides or 
standards S to move in and out for taking out or reptacing 
the hammer H, or to take up wear and tear. 

Referring again to figs. 1, 2, 5, and 6, o is a fiy shaft 
driven by a band on the fast pulley p. On this shaft is 
keyed a pinion q that gears into a spur wheel r, having 
fastened to it a ratchet wheel s ; these rotate freely on the 
shaft t, on which is keyed a lever , carrying a pawl v, 
retained by the spiral spring w on the adjustable pin JT. As 
the pawl engages the ratchet wheel s the latter drives the 
crank shaft t in the direction of the arrow y, causing the 
crank to uncoil the lud 2, at the same time coil up the 
band 4 and raise the hammer H. 



DETAILS OF AUTOMATIC DROP-HAMMER. 211 

As the crank z, with the lever M, return towards the 
bottom centre the pawl v catches against the shield 8, which 
serves to disengage the pawl from the ratchet wheel *, and 
keeps it out, allowing the ratchet wheel to continue its rotation 
without rotating the crank shaft L Simultaneously with this 
the lever u forces the flipper bar 9 shown in broken lines 
through the shield 8 aside, and then strikes against the 
eud of the second flipper bar 10, which serves as a stop, 
being supported by the spring 1 1 against the nut on the 
bolt 12. If it is desired to let the hammer fall downward 
pressure is applied on the treadle 14, carried by the levers 
15, and connected to the flipper bar 10 by the rocking levers 
and down rod. 

It will be clearly seen that the pawl v on the lever u is 
still kept out of gear of the teeth of the ratchet wheel by 
the outward extension of the arc-shaped shield 8 during the 
fall of the hammer, but when the latter is nearing the bed, 
the pawl passes off the upper end of the shield 8, and 
by the pressure of the spring w it again engages with the 
teeth of the ratchet wheel, aud consequently the hammer is 
again raised to the top of its lift. Any rebound from spring 
11 is resisted by the spring 13 on the opposite flipper bar 9. 
Xear the outer end of the shaft o is a loose pulley k, and 
adjoining this is keyed a flywheel I, which is used for raising 
the hammer up by hand for tool-setting purposes. The 
automatic safety catch J is made adjustable in the slot. 

Fig. 7 is a section of the standard S. The hammer can 
be adjusted for any height by means of screw 23 and crank- 
pin 24 in the slot of the crank Z. A rod 25 is connected 
to the treadle lever. On this rod is a sliding clip L, which 
overhangs the tail end of the catch J. As the treadle 14 is 
depressed to pull down the flipper bar 10 it also withdraws 
the catch J out of the path of the hammer before the latter 
commences to fall. 

The springs 27, which are fastened to the treadle levers 
15, are for keeping the flipper bar 10 in gear and the catch 
J under the hammer H. 

Fig. 6 shows in section the detail of the parts used to 
effect the crank pin adjustment. The other extremity of 
this pin is provided with a nut which tightens upon a 



212 



MACHINES FOR SHEET METAL WORK. 



shoulder, allowing the bush part 34 to be free to rotate on 
the pin 24. On the outer end of the bush part 34 is another 
screwed collar 35 ; this tightens up against a pair of divided 




Fio. 



STAMP HAMMER RAISED BY FRICTION. 213 




214 MACHINES FOR SHEET METAL WORK. 

clip plates 36, between which is held the slotted connecting 
bar 37. In case of heavy hammers it may be preferred to 
use a toothed rack and pinion instead of bands. 

Figs. 3 and 4 show this modification. H is the hammer 
to which a rack 38 is connected, this gears into a pinion 39 
and is guided by the rollers 40. On the outer end of the 
spindle 6 is fixed another pinion 42, about half the size of 
the pinion 39, and into this works a rack 43, kept in gear 
by rollers 44. Frame 45 swivels on the spindle 6 in order 
to conform to the angular movement of the rack around the 
pinion 42, caused by the circular motion of the crank Z. 

The power drop-stamp, fig. 209, is of similar construction 
to that seen at fig. 208, the only difference being that the 
latter would be worked by an overhead shaft. The stamp, 
fig. 209, is self-contained ; the belt is attached to the 
hammer and brought over the flange pulley, which is kept 
continuously rotating. When the hammer is required to be 
mised the belt is drawn tight, and the pulley instantly grips 
the belt and raises the hammer. Both are largely used for 
finishing seamless-drawn hollow-ware, which, after coming out 
of the drawing or raising press, have certain imperfections 
in them, such as buckles or wrinkles and round corners, 
which need bringing up sharp. The machine, fig. 209, is 
also used in the manufacture of labels, and for embossment 
which requires boldly bringing out. 

Another style of drop-stamp is seen at fig. 210. In this 
case the belt for raising the hammer is dispensed with, and 
in its place are introduced special rollers and a board. On 
depressing the foot treadle the friction rollers at the top are 
brought into contact with the board, thus raising the 
hammer. The board is automatically released and the 
hammer then descends. This drop-stamp is also used 
extensively for light forging work, such as articles used in 
the cutlery trades, locks, keys, pistols, &c. The movement 
of the hammer is controlled by a hand lever pivoted on the 
base block When a blow is required this handle is pressed 
down, causing the hammer to have a clear drop upon the 
work under operation, it then rises automatically to the top 
of its stroke, where it remains till the hand lever is again 
pressed down to have the blow repeated. 



SELECTING SPECIAL AUTOMATICS 215 



CHAPTER XVI. 

AUTOMATICS AND MACHINE TOOLS. 

IT is necessary for those who are fitting out new factories to 
have had a reasonably extensive experience, in order that 
commercial success may result. It is important to emphasise 
this, particularly as regards automatic machinery, a?, partially 
owing to the " booming " of American automatics, there is a 
probability that this class of machinery will for some years 
to come be looked upon as an absolute necessity for the 
successful working of a manufacturing concern. This may 
possibly result in a point being reached when a reaction will 
occur against the use of so many automatics. The subject 
of rapid and accurate production by special automatic 
machinery is an important one, but, as in many other 
subjects, there is more than one standpoint from which the 
matter may be viewed. The modern manufacturer recognises 
the value of special machines and tools that may be purchased 
and successfully used for producing thousands of similar 
articles, all finished to some particular and definite shape and 
size. But the question as to the advisability of adopting an 
automatic machine for the production of any new and special 
article from sheet metal is one that frequently calls for 
special j udgment and care in the decision, not only to decide 
upon the methods and number of processes through which 
the article shall be passed, but to select the most suitable 
machine for the work. In a cycle, motor car, gun or 
ammunition works there are sections of the work that can be 
rapidly and accurately produced by automatics, attended by 
unskilled labour. 

The author trusts that he will not be misunderstood by 
students, neither does he desire to contend that where 
considerable quantities of any particular article are required 
automatic machines should not be used. But there is a 
great tendency in modern times for automatics to be required 
for all purposes, and whilst their use should be encouraged, 
when it is possible to obtain beneficial results, there is a 
limit to their successful and economical employment. 



216 MACHINES FOE SHEET METAL WORK. 

The capstan lathe is an example of the successful applica- 
tion of a special machine. Its employment for a variety of 
purposes frequently necessitates modifications in design, so 
as to ensure of its being equally effective on various classes 
of work. 

As an example of an automatic machine well known in 
this country we may consider the wire nail, rivet, and panel- 
pin machine, where a coil of wire is placed upon a swift, the 
wire being automatically fed through the machine by a grip- 
feed, whereby thousands of nails, rivets, or panel-pins can be 
made before the end of the coil is reached, each nail being 
headed, pointed, then knocked into a box under the machine. 
Again, there are the tack and tingle machines, where a 
narrow strip of metal is placed in a feeding tube and 
automatically turned upon one side, and then the other ; at 
the same time the strip is carried forward, or fed along the 
tube, by means of a weight fastened to a piece of cord or 
string. Machines of this kind are generally attended by girls, 
and the tools are ground and set by the tool maker. The 
making of an umbrella rib and stretcher is another excellent 
example of automatic wire machinery, where the rib or 
stretcher is flattened, pierced both ends, and cropped or cut 
off automatically at the rate of 78 per minute. The tools 
for such machines are shown at fig. Ill; and, returning to 
sheet metal, button-making from a coil of sheet metal, also 
the cutting and cupping of blanks as in small arms ammu- 
nition, are examples of work being done automatically. 
Many excellent examples of automatic machines may be seen 
in the textile industries, in spinning, weaving, and knitting. 

The great thing to aim for is suitable machinery and 
tools having the least possible complication in their design. 
It is often the case with metal-working machinery that an 
automatic machine will work well for a short time, producing 
perfect work, then go suddenly wrong, making it necessary 
to have an experienced operator to work it, and it is 
questionable whether there is any great advantage to be 
gained. One example of automatic machine which may be 
mentioned as giving no special advantages, would be a 
machine for automatically drilling four blocks of a cycle chain 
at one operation. The care and attention required for a 



MACHINES USED FOR TOOL MAKING. 217 

perfect result make it doubtful whether there would be any 
advantage whatever by its adoption. 

However, an instance is known where one competent 
mechanic, with two young assistants, successfully superin- 
tended sixty girl operators who were drilling these same 
steel chain blocks, each operator handling a small single- 
spindle vertical drilling machine, and fastening the block to 
be drilled in the small jig shown at figs. 106 and 107. The 
work in this instance was proved to have been done more 
accurately and rapidly that could possibly be done in the 
special automatic machines which were being used in the 
same works. In cases where a small quantity of an article 
only is required, or where the demand is likely to be 
temporary, instances that do not really justify the outlay for 
a special machine, the mechanic or tool maker must devise 
some suitable method of utilising what machines and tools 
he has at hand, to enable the work to be turned out 
accurately ; and providing he has in the tool room or fitting 
shop, the usual ordinary machine tools, it is not unreasonable 
to expect him to prepare his temporary tools and jigs. 
One or two examples will illustrate the principal methods 
by which their accuracy may be accomplished. Previous to 
these examples we will indicate the principal machine tools 
and their uses that one would expect to see in a medium- 
sized tool room, and follow on by making reference to actual 
tools that have been made and illustrated in these articles. 

The manner of applying the methods must necessarily be 
left to the mechanic how best to use and develop them to 
meet his own particular requirements. If he does this, he 
will necessarily develop his powers of independent thought, 
which is so essential to the success of a tool maker who has 
a limited supply of special appliances at hand from which to 
execute his work. 

The lathe may be truly said to stand of first importance 
in the equipment of a tool room which has to deal with 
press tools. A useful 6 in. centre tool-maker's lathe is 
represented at fig. 211. The headstock is double-geared, has 
steel spindle, with a 1 in. hole through its entire length. 
The three-step cone is driven by a 2 in. belt. A convenient 
reversing motion is fitted for operating the sliding, surfacing, 



218 MACHINES FOR SHEET METAL WORK. 

and screw-cutting arrangement, and in some instances two 
rows of division holes are drilled on the face of the main 
wheel, and an index peg is attached to the headstock, and 
the loose headstock or poppet is adjustable for taper turning. 
It will be noticed that the compound slide-rest is fitted 
with an ordinary tool holder of the pillar form, the turning 
tool being held by means of a set-pin screwed down from the 
top end of the pillar. This type of tool holder, though con- 
venient for quickly placing and fixing a turning tool in 




position, and useful for light work, is open to the objection 
of the tool tilting when heavy cuts are being taken. A far 
better and safer tool holder is that consisting of two clamp 
plates P, P, held down by four pins (see fig. 212), which is a 
plan of the headstock and compound slide-rest. The turning 
tool T is operating upon a stamp die D, which is held in the 
chuck C. This "lathe can be used for all ordinary tool 
turning within its range of size ; borinsr, cylindrical cutting, 
cupping and drawing dies (figs. 78, 79, and 80) ; turning and 
facing punches, such as those seen at figs. 82, 87, 94, 95 ; 
and a variety of other work, as instanced at figs. 70 and 111; 
turning former (fig. 116), or the rollers (fig. 119). 



LATHE FOB BORING A STAMP DIE. 



219 




220 



MACHINES FOR SHEET METAL WORK. 



A sliding, surfacing, and screw-cutting lathe of 9 in. 
centre, having 9ft. bed, fitted with gap, is seen at fig. 213. 
This lathe, in addition to being convenient for ordinary tool 
making, may be used for turning and boring the larger dies 
and punches. A lathe of this size and design is capable of 
executing a great range and variety of work, from dealing 
with a piercing punch T ^ in. diameter to boring a bevel 
wheel 2 ft. diameter. At fig. 214 the lathe will be seen 
screw-cuttirg a drawing punch D P, on its shank S. Other 




examples of work carried out on this lathe would be that of 
boring and screw-cutting cross of bolster B, fig. 95, and 
making the setting-up pins, fig. 100, and the chuck, fig. 122. 

The shaping machine, fig. 215, is a 12 in. stroke, double- 
geared, and self-acting shaper, being also provided with 
a circular motion, so useful on sheet metal tool work. This 
circular motion will be seen above the work table immediately 
below the tool holder. 

The shaping machine can be used to great advantage when 
its use is understood and it is adapted to suit the existing 
conditions of the shop. At fig. 216 the shaping tool is seen 
operating upon the circular end of a cutting-out punch, the 
circular motion being put into operation for this purpose. 
On referring back to figs. 87, 88, and 89, the usefulness of a 
shaping machine will be apparent. The same may be said of 
fig. 92, since the machine could be used for roughing-out the 



SCREW-CUTTING A PUNCH SHANK. 221 




222 MACHINES FOE SHEET METAL WORK. 

drift. In addition to its use in the production of cutting 
punches, large dies and cutting-out beds may be readily 
surfaced top and bottom and on their edges by means of the 
shaping machine. 

A great amount of time and labour may be saved in the 
preparation of cutting beds by a proper use of the drilling 




Fio. 215. 

machine. That shown in fig. 217 has six speeds provided 
by means of a three-speed cone on counter shaft, and a two- 
speed cone on the spindle. The spindle cone runs on a 
bush attached to the frame, and drives the spindle by means 
of two keys in feather keyways, thereby removing all strain 
on the spindle from the pull of the belt The spiudlo has 
a ball thrust, ensuring great sensitiveness and freedom from 
breaking drills, and the spindle is balanced by a flat coiled 



THE USE OF A SHAPING MACHINE. 



223 



spring. The top table swings away, leaving the centreing 
arrangement for centre-drilling the ends of cylindrical tools, 
spindles, and shafts. There is also a circular swivel table 
available under the drill for use on special work. 




Another vertical drilling machine, capable of dealing with 
the larger work, is shown at fig. 218. This machine is of 
suitable design and construction to meet with the general 
requirements of both the tool and fitting shops, since it 



224 MACHINES FOR SHEET METAL WORK. 

embodies all the modern improvements for rapid and easy 
manipulation. The spindle is balanced, is fitted with ball 
thrust, and driven by two keys. The back gear is enclosed 




Fio. 217. 



in the cone pulley and can be instantly engaged by the 
movements of the lever, and the machine-cut bevel gear, 



GENERAL PURPOSE DRILLING MACHINE. 



225 



seen on the top end of the spindle, is enclosed. The feed 
is automatic and has self-acting variable stop motion for use 
when drilling accurately to depth, and a reversing motion 




FIG. 218. 



for tapping is provided, consisting of three bevel gears and 
clutch between, the clutch being operated by a lever placed 
in a convenient position on front of the machine. 
16wp 



MACHINES FOR SHEET METAL WORK. 



The table may be raised and lowered on the column by 
bevel-wheel gear and screw, and may >>e swivelled out of 
the way when it is required to bring a heavy casting under 
the drill. But for the purpose of press-tool work it will be 
necessary to use the table, in a position ut some distance up 
the column. The sketch, fig. 219, represents the drilling 





FIG. 21H. 

machine (shown in plan), operating upon a die </, intended 
for use in cutting sheet-steel blanks, and is an instructive 
example of the iise to which the drilling machine may IK? put 
for such work. A, B, C, and D represent the four stages in 
the progress of the drilling. Beginning at A, we see the 
shape of the blank marked out, and one hole has been 
drilled at end M, forming one end of the blank. In the 
next stage, B, we have the two end holes plugged up, ready 



METHOD OF DRILLING A CUTTING DIE. 227 

for the holes at either side of the plug (at end K) to be 
drilled, whilst at end J the hole at one side of the plug has 
been drilled, this drilling having removed a portion of the 
plug. In the third stage, C, two plugs are shown in the " 
holes at both ends, and it has been necessary to file flats on 
the plugs to get them into place ready for the third holes to 
be drilled in either end of the die. The plugging up of the 
holes may appear to some to be a trouble, but whenever a 
drill can be used in making a cutting bed to form any 
portion of the outline of its cutting edge, it is very much 
cheaper and satisfactory than if done by the ordinary 
method of chipping and filing. In the fourth stage, D, the 
three holes that have been drilled at end F clearly show the 
shape at one end as it will appear on the blank when cut, 
and at end G when the two plugs have been removed the 
same shape will appear there. It will further be noticed in 
sketch D that a series of small holes have been drilled, so 
that a small amount of chipping with a thin chisel will 
remove the centre piece E, ready for the two sides to be 
finished. A study of fig. 91 will further demonstrate the 
use of plugging and drilling, and the amount of drilling 
required to be done on the tools. Fig. 95 will clearly 
indicate that a drilling machine need not stand idle in a shop 
where press tools are manufactured. 

The use of drilling and profiling machines has long been 
associated with the manufacture of small arms and sewing 
machines. 

The chief application of the profiling machine was the 
formation of gun and pistol trigger action, the milling 
machine being chiefly employed in the preparation of the 
various cutters used in shaping the members of the gun, 
pistol, and sewing machines. Recent developments in 
milling operations have extended their use in many direc- 
tions, and the advantages of this class of machine are 
worthy of receiving more attention from the sheet-metal 
worker and others not directly associated with mechanical 
engineering than they hitherto have done. 

The milling machine, fig. 220, is an example of a modern 
machine fitted with the latest improvements and con- 
veniences, suitable for the production of articles of small- 



228 



MACHINES FOR SHEET MET A I. WORK. 



arms, cycle components, brass work, and for general 
engineering purposes. The headstock has a hardened and 
ground spindle running in conical bearings, a hole being 
bored through the entire length of the spindle, which 
facilitates the holding and removal of the cutter mandrel, 
the taper hole in the front end of spindle being bored to 
the Morse standard. 




FKJ. 220. 

Two solid projections are formed on the end of the spindle, 
and these fit freely in milled slots in the mandrel collar, thus 
providing a positive drive, so that the driving of the cutter 
mandrel is not dependent upon the friction of the taper. 
The mandrel steady is an internal cone bush of suitable 
taper, and the steady arm is cylindrical and can be easily 
removed when 



USE OF THE PROFILING MACHINE. 



229 



An effective brace is provided to tie the cylindrical steady- 
bar rigidly to the knee bracket of the machine for reducing 
the vibration to a minimum. The work-table has tee slots 
to receive the holding-down bolts, and the table has ample 
space to allow of several gangs of work being milled side 
by side, as is in some instances required. The knee bracket 
is fitted with screw r and bevel gear for elevating, and has 




vertical stops and indicated discs for the purpose of setting 
on the cuts accurately. Automatic feed devices are pro- 
vided with a trip gear, which stops the feed at any desired 
position, and adjustments are provided to enable the feed 
belts to be shortened or lengthened within reasonable limits 



230 



MACHINES FOR SHEET METAL \\OKK. 



without cutting them. When suitable cutters are at hand 
ordinary cutting beds may be cheaply milled top, bottom, 
and edges, besides such tools as those seen at figs. 87, 94, 
and similar work. A typical profiling machine is repre- 
sented at fig. '221. The vertical slide has a central stop- 
motion, and the lever for working the slide is also placed 



M.T 





SO 




in a central position. The transverse slide runs on rollers, 
thereby making it very free to handle ; it can be actuated by 
a screw and worm fesd motion in addition to the ordinary 
lever, and is furnished with two locking bolts, to clamp it in 
any fixed position, and stops are provided to allow for milling 
to definite lengths. The work-table is actuated by wheels 
and pinion, and is provided with compensating devices to 
take up wear and ensure perfectly steady cutting. The 
principle of the profiling machine is indicated at fig. 222. 
A cutting-out l>ed D is fixed upon the work-table M T, and 
the milling cutter c is carried by a vertical spindle attached 
to the slide. A steel pattern P is fixed by the side of the 



PROFILING A CUTTING-OUT BED. 231 

die D ; this pattern is also known as a template or former, 
and is made the exact contour as required to be formed 
upon the die D. At one side of the spindle which carries 
the cutter a tracing or feeling peg t is fixed ; this peg is 
turned taper, so that by lowering or raising the peg the 
cutter c will be drawn to or from the die D, as the case 
may be. The feeler is kept hard up against the former P 
by means of a chain and weight attached to the slide ; and 




since the distance between the feeler t and the cutter c is 
always the same, it will be readily understood that as the 
feeler t travels over the contour of the pattern P, so the 
cutter c will travel round the die D, thereby producing 
the required contour thereon. Another example of die that 
may be easily formed by profiling is the die S D, intended 
for cutting spoon blanks, and the profiling machine may be 
as readily used for external as internal work. A study 
of the various and peculiar shapes of cutting dies to be met 
with in any sheet-metal works will give an idea as to the 
machine's usefulness. In a tool room, where large quantities 



232 



MACHINES FOR SHEET METAL WORK 



of small screws are required for joining up the various parts 
of dies, punches, and lx>lsters, the screw-nicking machine, 
fig. 223, will be a useful addition for milling the slits in 
the heads of screws ; and the screw-polishing machine, 
fig. 224, may be used for polishing the small screws, pins, 
and piercing punches, which would otherwise occupy the 
lathe. 

The ordinary machine vice, owing to the uplift of the loose 
jaw and unreliability of the fixed jaw, has hitherto not l>een 




of much use for dealing with tool work of any great 
accuracy, and the special machine vice, known as Taylor's 
patent, has many advantages. In making this vice great cure 
is taken as regards parallelism of the upper and lower faces 
of the vice. Any work done upon the upper surface of the 
article may be depended upon to be true with its under 
surface, and the necessity of hammering down the article 
held in the vice is abolished. 



SPECIAL MACHINE VICE. 



The direct action of the screw enables the necessary 
degree of tightness to be obtained with the expenditure of 
less force than is required with an ordinary vice, and, in 
consequence of its favourable position, the screw escapes the 




dirt and swarf of the cuttings. The " Taylor " vice is 
represented at figs. 225 and 226. It will be seen that the 
loose jaw is free to slide backwards and forwards in the longi- 
tudinal slot of the vice, as is also the grip plate when tilted 




slightly forward, thereby disengaging the two strong teeth 
from those on the body of the vice. Fig. 226 is a section of 
part of the vice, showing that the rear faces of the steel jaw 
plates C, C are inclined, thus causing them when an article 



234 



MACHINES FOK SHEET METAL WORK. 



is gripped to slide downwards for a very short distance, 
carrying with them the article held, the pin holes in the 
jaws being slotted to allow of this motion. E, E are screws 
and springs holding jaw plates back. These plates are raised 




again when the article being held is released, by. simple 
springs working in the recesses D, D, shown at the bottom of 
each plate. The small cap screw F keeps water and dirt 
from entering the pin hole. A piece of hardened steel is 




Fio. 228. 



fixed in the centre at the back of the moveable jaw to 
receive the pressure of the screw. These vices are some- 
times provided with special vertical tilting adjustable angle 
plates, forming a convenient attachment for use on milling 
and shaping machines when employed on general tool work. 



QUADRANT DIVIDING HEAD STOCKS. 235 

The dividing headstocks, represented at figs. 227, 228, 
and 229, are for general use on either milling or shaping 
machines. Fig. 227 is a 6 in. centre plain set of heads, and 
admits 15 inches between the centres, a notched dividing 
plate being attached thereto. Fig. 228 is a set of 4i in. 
plain heads, admitting 12 inches between the centres. This 
apparatus is provided with a drilled drum of large diameter, 
having nine rows of divisions, with the following numbers 
120, 100, 90, 88, 72, 64, 42, 36, 26. 

The quadrant dividing headstock, fig. 229, is fitted with a 
switching block, graduated to set the spindle to any angle, 




from a horizontal to a vertical position, and provided for 
cutting cutters of any angle. The divisions are obtained 
by means of worm and worm wheel, and with the plate 
supplied most numbers can be obtained from 2 to 360 
divisions. The index fingers can be set to any division, and 
by their use the necessity of counting and the danger of 
mistake are entirely avoided. 



236 



MACHINES FOK SHEET METAL WORK. 



CHAPTER XVII. 
TOOLS AND JIGS FOK REPETITION WORK. 

THE lathe test indicator, fig. 232, is for use in setting central 
any point or hole in a piece of work to be operated upon in 
a lathe or upon a lathe face-plate. It may also be used for 
testing lathe centres, shafting, or other work held between 



lathe centres, the inside or outside of cylinders, pulleys, etc., 
and all work of a similar class. The tool is of such size as 
to be held conveniently in the tool post of a lathe ; the bar is 




drop-forged and formed at the end to receive an universal 
joint for supporting the finger. A clamp nut is provided 
for clamping the joint when it is desired to have only a 
vertical movement to the finger, as in testing pieces held 



TYPES OF LITHE TEST INDICATORS. 237 

between lathe centres. The bushing which holds the finger 
is split, thus allowing the finger to be adjusted to any 
required length, and clamped in position. The finger holder 
is provided with two fingers ; either one of these may be 
quickly attached; one finger is ground to an angle of 60 deg. 
and the other is bent for inside and outside testing. A 
spiral spring is provided for holding the finger against the 
work with an even pressure. 

An improved instrument known as a centre-tester, fig. 233, 
is of a special design for use in adjusting and locating central 




any point or hole in a piece of work, which is to be operated 
upon, in a chuck or upon a face-plate. The tester is shown 
fixed in a tool post ready for use ; a steel bead (not shown) is 
carried on the needle, it slips over the point of same, when 
used for inside work. The instrument is joined to a tool 
post shank by a flexible steel ribbon, with sufficient spring 
to properly hold the needle in contact with the work. The 
ball through which the indicating needle passes is pivoted 



238 



MACHINES FOR SHEET METAL WORK. 



to form an universal joint, but may be instantly converted 
into a single joint for a tilting motion, by tightening the 
knurled nut. 




Another test indicator, fig. 234, is especially serviceable to 
those who have the erecting or inspecting of high-class 
machines, as it is possible by its use to readily determine 
the degree of inaccuracy of a surface on the top, bottom, or 
side of a piece of work, or to easily ascertain the amount 



Fio. 230. 

of end movement, for example, of a spindle, or the extent 
to which it runs out of truth. The illustrations, figs. 235, 
236, 237, and 238, show a few of the many applications of 
the test indicator. The upright post or stand may be 



METHODS OF APPLYING TEST INDICATOKS. 239 

clamped at any point upon the base by the thumb nut, 
and the sleeve which carries the arm may be fastened at any 
height on the post, or turned around the post to bring the 




arm on either side. The arm turns in the sleeve, and may 
be set at any angle relative to the base ; it may be converted 
so that the point brought in contact with the work will be 
downward rather than in the position shown in fig. 234, or 




it can be removed from the post and used independently. A 
split block and an angular post are furnished with this test 
indicator, for use in the tool-post of a lathe. The movement 



240 



MACHINES FOR SHEET METAL WOKK. 



of the point that bears against the work is magnified a 
number of times by the length of the index finger, and can 
be easily read upon the scale. The finger can be adjusted 
and brought to zero by the knurled screw shown. It is 
enclosed and protected from injury, and stops are provided 
for use on the underside of the base against perpendicular or 
angular surfaces ; the length of the base is 8 in., the height 
of the post 9 in., and the graduations read to thousandths of 
an inch. 

One method of setting for boring two holes at a definite 
distance from centre to centre is represented at fig. 239. For 
example, the holes required to be bored in a steel die A are 




Bl- 








\ ^' 


o 




Pi 



Jt in. diameter, and their centres 1 in. apart. F P 1 represents a 
fathe face-plate, upon which is fixed the steel die ; this is shown 
set in the position required for the first hole to be l>ored. S is 
an iron plate to prevent the die A 1 from dropping. Another 
small iron stop plate SI, is to prevent the die A 1 from 
slipping sideways. The small iron straps or plates and bolts 
for holding the die upon the face plate are not shown. The 
setting of the die would be done with the assistance of the 
special centre tester as represented at figs. 232 and 233. 
Having bored the first hole, the die is moved along the stop- 
plati- S a sufficient distance to allow the packing piece 1* to 
lie introduced; this piece is filed up to measure exactly 1 in., 
and consequently the two holes in the die will be exactly 1 in. 



ACCURATELY BOEING TOOLS AND JIGS. 



241 



between their centres. This method is frequently used in 
first-class workshops, but although very useful under certain 
conditions, it is not a sure or reliable method. The least 
speck of dirt between the faces of P and A 2 will alter the 
measurement, besides special packing pieces being required 
for every different measurement. 

Another method of setting for boring holes is seen at fig. 
240, and may be depended on to give absolutely accurate 




FPI 



A bo 




o o 




Fio. 210. 

results. Referring to the figure it will be see that the die has 
been fixed by the aid of a centre tester, and the stop plate S 
brought up to the die, and the first hole bored. We will 
now trace the means by which the new position is found. 
Referring to the section it will be noticed that a standard 
| in. plug gauge B has been inserted into the first hole. 
17wp 



242 



MACHINES FOR SHEET METAL WORK. 



This | in. plug must necessarily be a good fit. A second 
plug A, which may be any diameter (in present instance 
T 6 ff in.), is made in the form of a lathe centre, and is fixed 
into the barrel of the movable headstock of the lathe. It 
will be readily seen that by means of these* two plugs it is 
easy to so fix the die A 2 upon- the face-plate as to enable 






3. P. 



holes to be bored at any required centre. Taking the 
example of the i in. holes of 1 in. centres, here we have 1 in. 
centres plus half ^ in., plus half Mu. = 1 -406 in. There- 
fore, when the micrometer gauge just passes over the plug?, 
then the die is set for holes at 1 in. centres. One practical 
application of the method represented at fig. 240 was boring 
the two holes in the standard die or cutting-out bed, fig. 91. 



ACCURATE METHODS OP DRILLING BY JIG. 



243 



Another method by which two or more holes may be 
drilled at any centres is shown at tig. 241. In this case the 
centres are fixed by means of steel bushes and packing 
pieces. To make the method readily understood, we may 
for simplicity still keep to the steel die having holes ^ in. 
diameter, and 1 in. centres. X is a piece of steel measuring 
5| in. in length, 2 in. wide, and 1 in. thick. This has a slot 
4 in. long and 1 in. wide running along the centre. Into 
this slot two steel bashes L in. diameter and 1| in. long are 
introduced, the bushes having ^ in. holes bored through 
them, and they are hardened and ground perfectly true. 




Then when these two bushes are brought together their 
centres will be exactly 1 in. apart, and since they are firmly 
fixed together by means of packing pieces and set pin, the 
whole arrangement becomes at once a simple form of 
drilling jig. The packing pieces being '250 in., -375 in., 
and - 5 in. thick, when placed between the pair of steel bushes 
the centres of these bushes will be 1 '250 in., 1 -375 in., and 
1 '5 in. apart respectively. 

At fig. 241 Z is a section showing the method by which 
No. 2 hole is drilled. The die D I is coupled to the drilling 
jig by means of a steel plug S P, and a |in. twist drill is 
passed down the second bush, and its point penetrates the 
die a short distance, sketch D 2, fig. 242. The next step 
is to pass a f in. or T 7 ^- in. twist drill through the die (see 
D 3) then finally pass the | in. twist through the bush and 
die (sketch D 4). This system has been adopted for making 



244 



MACHINES FOR SHEET METAL WORK. 



a variety of tools and jigs for drilling and piercing, and has 
been found useful and reliable. 

The sketches, figs. 243, 244, 245, indicate the usual 
method by which a piece of work to be bored is fixed upon 
the face-plate by bolts and strapping plates. These sketches 
further show the principle of the centre tester. Referring 
to fig. 24?, the steel die A is fixed upon the face-plate F P 




ready (in this instance) to have a hole bored in it. The 
die A is held by S and S 1 . There are two wood packing 
pieces W P between the straps and the face-plate. No stop 
plates are required on this work, since there is only one hole 
to be bored; but there are instances where it may sometimes 
be advisable to use one or more stop plates, so as to prevent 
the work being accidentally moved whilst boring as for 
example, when heavy boring cuts are being taken, or when 
a piece of work is of delicate strength and peculiar shape. 
In instances of this kind the stop plates, besides holding the 
work steady, also drive it in a similar manner to that that 



SETTING WORK UPON A LATHE FACE-PLATE. 



245 



the driving peg drives a lathe carrier when a shaft is being 
turned. 

The old method of setting work true upon a face-plate 
was to describe a large circle upon the surface, as at 0, fig. 
243. A pointed piece of steel was then fixed in the toolbox, 
the point being brought close up to the c rcle whilst the 
lathe was in motion, thus indicating if the circle ran true. 
This large circle is not necessary if a centre tester is used. 
It will be noticed that a smaller circle N is shown, which 
has been described from the centre dot C upon the die A, 




and is equal in diameter to the hole that is to be bored. At 
figs. 244 and 245 a ring R is seen, into which the steel rod 
a, having both ends pointed, is fixed, and another rod b, 
having one end drawn out to a long taper terminating at a 
point. These two rods a and b are in perfect alignment ; 
one end of rod a is held in the centre dot c of the die, whilst 
the other end is placed into another centre hole d of the 
holder B. This apparatus demonstrates the principle of the 
delicate special centre-testing instruments described in figs. 
232 and 233. As may be judged from the sketches shown at 
figs. 244 and 245, this is an apparatus that can be made in any 



246 MACHINES FOR SHEET METAL WORK. 

ordinary tool-room, and, though of rougher character than fig. 
233, it is very useful. The position of centre hole d, at fig. 24 1 , 
Would be determined by placing it against the lathe centre. 
B is fixed into the tool holder by the clamp plates D 
and D 1 . In fig. 245 it will be seen that the length of rod a 
is 2 in., whilst the distance from d to the extreme end of rod 



b is 10 in., or a ratio of 5 to 1. So that, when testing a 
piece of work for being set true, should the centre dot c run 
out of true ^V in., the extreme end of rod b would run out of 
true T/V in., thereby magnifying the inaccuracy. From this 
it will be readily understood that the centre tester is of 
great assistance when setting work. 



CHAPTER XVIII. 

INTERCHANGEABLE MACHINE PARTS. 

MACHINES of somewhat small and delicate design are fre- 
quently required in which their members must necessarily come 
together accurately and yet be interchangeable. A machine 
of this description is shown at fig. 246, as used for spinning 
the heads of rivets. A barrel B, having teeth formed upon 
a portion of its length, gears into a rack formed on the 
sleeve S, and as it rotates so the sleeve is advanced, carrying 
forward the spinning tools to operate upon the rivet head. 
Assuming that one dozen or more machines are to be made 
from this pattern, and that any pair of heads are expected 
to come together, and their centres to be in perfect align- 
ment, and farther that any barrel or any sleeve shall pass 
into and be a working fit in any one of the twenty-four or 
more headstocks, the work will necessarily be of a delicate 



248 MACHINES FOR SHEET METAL WORK. 



PREPARATION OF AN ACCURATE BORING JIG. 



249 



nature, and it is essential that special care be taken in the 
boring of the headstocks. With the very best class of tools 
and first-class workmen, it is questionable whether the parts 
could be made interchangeable, unless jigs are used. It is, 
however, possible, in these special instances, to insure 
that the heads be bored so that the results are perfectly 
reliable if suitable jigs, which may be of simple design, 
are provided for the purpose. To trace how these twenty- 
four headstocks may be bored will demonstrate the 
principle of the jig as applied to this class of work. In 
fig. 247 the casting H is planed out to receive the base 
of the headstocks to be bored. At fig. 249 four castings, 
A, B, C, and D, are seen, two of which are prepared 
to receive the boring bar E. Taking, for example, castings 
A and B, their bases must be planed to fit the jig bed H, 
and they are next set out at the required height, and bored 




upon the angle and face-plates of an ordinary lathe. The 
next step is to fix them upon the casting H, fig. 247, and 
introduce the boring bar E, which must be held by two 
collars (not shown), so that the bar can rotate in castings A 
and B, but not move in the direction of its length. A and 
B may have been set out and bored by a careful and com- 
petent turner, but are not likely to be absolutely perfect. 
The next step is to bore C and D in the same manner that 
A and B were bored, only the holes in the former must be, 
say, y 1 ^ in. larger in diameter, to enable the boring bar to 
rotate freely without touching the casting?, whilst the bar is 
being carried by the smaller holes in A and B. The reason 
for this will he understood by referring to fig. 247, where C 
is to be bored. The castings C and D, in their turn, are 
placed upon bed H, and are held down by plates and pins, 
only sufficient pressure being given to ensure keeping them 



250 



MACHINES FOR SHEET METAL WORK. 



down upon the bed, but to allow of them being moved along 
the bed under the pressure from a long set-screw. It will 
be noticed that casting A has been drilled and tapped at M, 




to receive the screw f seen at fig. 251. This set-screw is 
placed in the boss, and brought up against boss M 2 of casting 
C, thereby moving the latter along the bed to enable cutter 
O to bore the hole. From this it will be seen that, even 



&' 




supposing A and B to have been inaccurately bored, C and 
D are certain to be accurate, if reasonable care has been 
taken to see that the bar runs a good fit in A and B. 
Castings A and B may be thrown away, since they will not 



NECESSITY OF CORRECT TOOL SETTING. 251 

be required again. The boring bar just used 'is now sub- 
stituted by a larger boring bar E 1 . Fig. 248 shows headstock 
K being bored. This headstock K and all subsequent ones 
are, in their turn, moved along the casting by means of the 
long set-pin /, to enable the boring to be done. Another 
casting G, fig. 250, which is securely fastened to the bed H, 
carries the boring bar F, and forms a jig for boring the 
transverse hole to receive the barrel wheel B (seen at fig. 
246). In this case the boring bar travels along carrying the 
cutter P, whilst the headstock K is firmly fixed to the bed 
H. A part section of the jig is shown at fig. 251. It will 
be necessary to drill and tap a hole in casting C at boss M 2 
to receive the set-pin. There may appear to be a fair 
amount of labour required in making this jig, but a careful 
study of its action will demonstrate that its value as a safe- 
guard against inaccuracy will amply repay itself. 



CHAPTER XIX. 

PRESS TOOL-SETTING. 

THE old adage an incompetent workman finds fault with 
his tools is as true in press work as in any other industrial 
department. 

No matter how well designed and equipped a works may 
be, unless the shops are under good management, assisted by 
competent workmen, the result will be unsatisfactory. It 
would be beyond the province of these articles to give all the 
details necessary to explain how every machine should have 
its varied tools set for successful working. We will there- 
fore briefly draw attention to some few points of general 
application concerning the tools in this important section of 
machine working points that are to some extent over- 
looked or considered to be of little import, although they 
govern the quantity and quality of the production, besides 
affecting both the life of the machine and its tools, in 
addition to frequently resulting in power being lost or wasted 
in unproductive work. 



252 MACHINES FOR SHEET METAL WORK. 

Assuming that a first-class machine is supplied with 
thoroughly accurate tools, the next question is, naturally, the 
setting of these tools so as to enable the operator to produce 
good work quickly from the machine. This would in some 
instances be a simple matter which a careful machine 
attendant could manage. In other instances the tools may 
be of such a complicated nature, that a considerable amount 
of ability and experience may be required to set the tools. 
A few examples will demonstrate that this is so. In the 
case of cut-tach and tingle making, an experienced machine 
minder will have charge of from six to twelve machines ; he 
will both make, grind, and set the tools, but will have female 
operators to put the strip-iron into the machine, and attend 
its working. Wire-tach, rivet, panel-pin, wire-nail, staple, and 
split cotters is a class of work also requiring a skilled 
mechanic as chief minder, to make and set all tools, the 
wiring of the machine from the swift being carried out by 
female or male attendants, according to the size of the work 
i.e., the weight of the coil of wire from which the nails are 
made. Thus in the case of nail machinery the tool-maker 
is held responsible for the correct setting of his own tools, 
besides the supervision of the machinery when in motion. 

As another example, we may consider metal-stamping, 
drop-forging, and similar work. The stamping or forging dies 
will be made in a tool-room, thence passed into the hands of 
an experienced stamper, capable of setting his own tools in 
the stamp, though he be neither a tool-maker nor mechanic. 
In other instances the stampers, both male and female, may 
not be capable of setting tools, but merely proficient in 
placing the metal between the diet and working the stump. 
Regarding press tool-setting, it may be truly said that, as a 
general rule, in small workshops this question is considered 
to be of minor importance, although a great waste of time 
and material is caused, due alone to imperfect tool-setting. 

An instance came under the authors notice. In a factory 
where hundreds of machines were in use the more important 
tools and machines were made in one large fitting and tool- 
making shop in a central part of the works, thence supplied 
to the various work-rooms, each under the super vison of a 
tool-setter having charge of a number of machines and 



TROUBLES CAUSED BY CARELESS TOOL SETTING. 253 

presses, the operators being pieceworkers. It was noticed 
that in a certain work-room an unusually heavy demand for 
tool renewals was experienced. The machines which had 
been condemned by the tool-setter were replaced with new 
arid first-class machines ; but neither the quantity nor quality 
of the output improved, nor the demand for tools reduced 
with the new machines. A competent machine-tool fitter 
was despatched to carefully examine the machines and 
investigate matters generally, when it was found that the 
press-rams which had been properly adjusted in the 
machine-tool shop had been re-adjusted by the tool-setter. 
The slides and rams of the machines were found to have been 
tightened, requiring considerably more power to drive the 
machines, besides galling the slides, rams, and guide strips 
in fact so much so that re-planing was necessary. The 
cause of all this trouble was traced to defective tool-setting, 
and the tool-setter had gripped up the rams, thinking 
thereby to prevent the tools kicking. In the other work- 
rooms, where the adjustments of the machines had not been 
tampered with, no trouble was experienced. 

If the tool-setter finds a slide or ram working slack, he 
should immediately draw the attention of the machine-tool 
fitter to the defect. If a ram is to work properly, it requires 
careful adjusting, so that it may work up and down its 
stroke quite freely, yet have no play or be likely to lick 
when working the tools. 

Any slide or ram is difficult to set accurately, and the 
most troublesome to set is the fly-press ram of square 
pattern, as these may be adjusted so tightly that they can be 
scarcely moved by the screw, yet they will kick sufficiently 
to ruin a pair of cutting-out, blanking, or piercing tools at 
the first blow. 

Although it has been mentioned as being advisable, if 
possible, to have someone to do the tool-setting who has had 
some training in tool-making, there are instances known 
where workmen, without any previous knowledge of working 
machine tools of any kind, have been trained to set tools in 
the press, and have become quite expert and valuable tool- 
setters. 

The question of tool-setting is an important one, and 



254 



MACHINES FOR SHEET METAL WORK. 



should always be kept in view when tools are being designed. 
It is, however, too often the case that no thought whatever 
is given to this question ; consequently a set of tools say, 
for example, a punch and die are made before any thought 
is given to either the tool-setting or how the metal blanks 
are to be stripped from the punch. The result is that 
probably an unsuitable stripper is used, and a rough method 
of setting adopted. The method of stripping the scrap 



A IS. I s.P 




FlO. 253. 

metal in press work plays a very important part upon the 
successful action, as well as upon the life, of the tools ; 
particularly is this so in the case of small delicate press- 
tools, where a crude stripper arrangement will frequently 
make bad work, in addition to damaging or breaking the 
tools. 

The old system of stripping, which is even now practised 
to a certain extent, is to have a slot cast through the back 
of the press in single-sided presses, and in double-sided 



COMMON STRIPPER ARRANGEMENTS AND WASTE WORK. 255 

presses a slot cast through each side of the press-frame 
casting. This slot is of sufficient width and depth to 
receive a hexagonal-headed bolt, and allow of the bolt being 
raised up and down for adjustment. A wrought-iron angle 
forging is fastened to the press-frame by means of the bolt 
and a strap plate, the bolt passing through the angle-iron 
and the slot in the press-frame. The angle-iron can either 
be made to act as a stripper, or some other form of stripper 
may be mounted and securely fastened to it. An angle- 
iron stripper will be seen at fig. 252. This angle-plate 
method of stripping is a rough-and ready one, and is used 
with some success for rough sheet-iron work. It cannot, 
however, be recommended with safety for general work for 
several reasons. 

Firstly, this stripper arrangement depends too much 
upon the ability and expertness of the tool-setter. Secondly, 
this stripper is apt to be used for too many kinds of work. 
Thirdly, as the stripper is held against the face of the 
press-frame by a bolt, there is considerable leverage upon 
the angle-iron, which springs the whole stripper arrange- 
ment. 

In many instances a tool-setter will take advantage of 
this springing action for the purpose of throwing the work 
from the tools, and it is done in the following manner : 
After a blank is pierced, the punch on the return stroke 
carries the blank up to the stripper, and this in turn forces 
the stripper to spring upwards, and directly the blank is 
removed from the punch the pressure is released from the 
stripper, which now returns to its normal position, and 
thereby throws the blank some distance from the tools. 
This fact will demonstrate that a fair amount of springing 
action occurs with this type of stripper, which is detrimental 
to both work and tools. 

The reason why the angle-iron type of stripper, fig. 252, 
is used so extensively is that it can be used for various 
sizes of work, even though there may be a large clearance 
between the piercing punch and stripper hole, which may 
cause the blank to be bent or otherwise distorted during the 
process of stripping. 

Suppose twenty sets of tools, all differing, are to be used 



256 MACHINES KOK SHEET MKTAL WORK. 

in a particular power or screw press ; one angle-plate stripper 
can be used for the twenty sets of tools by using various 
iron-plates (see fig. 252), where the additional stripper-plate 
S P is attached to the angle-plate stripper A I S. The only 
instance where this type of stripper has been known to work 
successfully was when the angle-plate forging was planed 
square, and had a rib upon the back, as fig. 252 at R, to fit 
the slot in the press-frame. Also when used on a double- 




sided press, and two separate and well-made angle-plates 
have been fixed, one on either side of the press-frame, set 
level with each other, and planed upon the top (see fig. 253 
at T), to receive various special stripper- plate forgings, which 
have in turn been planed, bored, and turned perfectly square 
and true, as at F. It is, however, seldom that one can meet 
with strippers of this type made and finished in the manner 
they should be if good work is to result. 

From what has here been mentioned in reference to the 
angle plate type of stripper, it will be readily understood 
that, when possible, it is advisable to dispense with it, and 
substitute a more reliable form. 



CORRECT SETTING OF PUNCH, BED, AND STRIPPER. 257 

An excellent combined stripper-plate and metal-guide is 
shown at figs. 103, 104, and 105, arranged to be fixed to the 
die bolster, and intended for cutting chain-link blanks. Jn 
this case the stripper is raised and lowered by means of lock- 
nuts, and the two small bars across the underside of the 
stripper-plate are placed at a sufficient distance apart to 
admit the steel strip from which the blanks are to be cut. 
When a set of tools are fitted up in the manner shown at 
figs. 103, 104, and 105, the punch may be removed from 
the press after a batch of blanks have been cut, and punch, 
die, bolster, and stripper all stored away together ready for 
immediate future use. 

The proper method is to provide every bolster with its 
own stripper or strippers, which should be made suitable for 
the various sets of tools. It is necessary that the bolster 




be planed on the top, and have suitable holes drilled and 
tapped to receive the stripper holding-down pins. A 
stripper may either be fixed in this manner, or it may be 
attached as shown at figs. 103, 104, and 105. 

A stripper to work efficiently must be set at right angles 
to the side of a punch, and absolutely level with the top of 
the die, and the hole in the stripper should be of sufficient 
size to comfortably pass the punch. When a punch is 
raised up it should, after piercing a blank, bring the whole 
surface of the blank into contact with the under side of the 
stripper (see fig. 254) ; the blank will then be removed from 
the punch with an easy sliding action, and without placing 
any side strain upon the punch, as would happen if the 
stripper were set as shown at fig. 255. It will readily be 
18wp 



268 MACHINES FOR SHEET METAL WORK. 

seen in this figure that the slipper-plate S P is not set level ; 
consequently the blank touches at a and is off at b. When 
tools are set in this careless manner trouble will arise. 
Owing to the improper use of strippers and tools it is not 
unusual for much time to be wasted. 

It is interesting to trace the proper method of setting the 
tools seen at figs. 102 to 105. 

Firstly, the punch should be firmly fixed into the press- 
ram by means of the set-pin in the ram, the pin preferably 
being screwed up by a steel box-spanner, since it gives a 
better purchase than can be obtained by an ordinary 
spanner. Stamdly, after fixing the bed into the centre of 
the bolster, bring the latter under the punch, which 




carefully lower into the bed. Place the lx>lster holding- 
down pins into position, and lightly nip them dowu ; raise 
the punch and again carefully lower it into the bed, making 
quite certain that it does not come in contact with the 
cutting edge of the bed. Next screw down both holding- 
down pins, proceeding a little at a time first one pin, then 
the other. Thirdly, place the stripper in position on the 
leister, the guide-bars resting upon the top of the bed. 
Place a piece of metal upon the bed, and cut one blank ; the 
punch should then be raised up until the metal strip touches 
the under side of the stripper, which may now be set level 
with the metal strip. If instead of the stripper being fixed 
by lock-nuts it had been fastened upon the top-surface of 
the bolster, it would not have l>een necessary to test for 
l>eiug level. The idea of using the lock-nuts in the tools, 
fig. 104, is to enable beds of various thicknesses to be used, 



THE STOP-PEG ON A CUTTING BED. 



259 



without the necessity of packing pieces. Now, suppose the 
tools which may have been working a few hours require 
grinding and re-setting, the bed-key can be driven out, 
fig. 102, and replaced after the bed has been ground, 
enabling the tools to be re-set in considerably less time than 
had the bolster been loosened. 

When cutting blanks from sheet-metal without the assist- 
ance of feed-rolls, it is usual to fix a stop-peg in the bed to 













p 








I-K 




B 





enable the operator to bring the metal in the proper position 
to cover the hole in the bed. Were it not for this peg, it 
would be practically impossible for an operator to leave a 
uniform amount of scrap metal between each pair of blanks. 
A bolster B and a bed D are shown at fig. 256, fitted with 
the stop-peg P, the end E of the metal M being brought up 
against the stop-peg whilst the first blank is cut Previous 



260 MACHINES FOR SHEET METAL WORK. 





O O 




B 




s 

1 o 







rJ- =t 


3 K 






^> 




GUIDE PLATE FIXED TO CUTTING-BED. 



261 



to the second blank being cut, it will be necessary to lift the 
metal over the peg P, so that it comes into the hole made 
by the cutting of the first blank ; this places the metal M in 
the proper position ready for the second blank to be cut. 
The bed is here seen fixed in position by the key K, and the 




stripper-plate S is secured upon the bolster casting at A. 
Fig. 257 is a plan of the stripper-plate, and it will be noticed 
that the hole in the stripper-plate is slightly larger than the 
hole in the cutting bed. 




The tools, fig. 258, are for piercing a round hole in the 
blanks that have been previously cut by the tools, figs. 256 
and 257. Referring to fig. 258, a guide plate G P is fixed 
upon the piercing die, to ensure the metal-blank M B being 
pierced centrally. 



202 



MACHINES FOR SHEET METAL WORK. 



The stripper S is fastened at A, and this part of the 
bolster casting is raised up a sufficient height to allow ti 
proper freedom of space between the stripper and guide 
plates. A plan of the piercing tools is shown at fig. 259, 
from which the position of the stripper and guide plates will 
be seen. 




Fig. 260 represents another type of bolster to receive a 
similar pair of piercing tools to those at figs. 258 and 259, 
the difference being, that whereas in fig. 260 the stripper- 
plate is fastened to the bolster at A, and the guide-plate is 



HEATING STEEL UNIFORMLY FOR HARDENING. 263 

fastened on to the bolster at H, in figs. 258 and 259 the 
guide-plate is fastened on to the bed itself. 

Another design of bolster and tools is shown at fig. 261. 
This set of tools is arranged for piercing the same blank as 
the tools, figs. 258, 259, and 260 were, but in the case of 
fig. 261 both the bolster and the bed are cylindrical in form. 

The stripper- plate S P is secured to the raised portion A 
of the bolster-casting B, whilst the guide-plate GP is fastened 
to the top of the bolster at r l\ Tj. Three set-pins, a, a 1 , a 2 , 
are intended to enable the tool-setter to move the bed about 
until it is set in the proper relative position with the guide- 
plate, to ensure that the blanks shall be pierced centrally. 

HARDENING AND TEMPERING. 

In the case of cutting, shearing, stamping, drawing, and 
similar tools that have to be hardened to enable them to 
deal with sheet metals, it is necessary to exercise special care 
in heating them to the required temperature before they are 
plunged into the water bath for cooling. The careful and 
uniform heating applies to all hardening, more or less, but 
it is of particular importance in the case of expensive dies 
or punches. The principal point is to watch that the tool 
be heated as gradually as possible, and too much stress 
cannot be placed upon the importance of care in harden- 
ing. It is not unusual to see a blacksmith or a toolmaker 
place a large die into a fire, heat one side red-hot, whilst the 
other side is nearly cold ; he will next turn the die round 
and heat that side which was cold, w r hilst that which was 
red-hot will get nearly cold again. The author has seen 
this done repeatedly, but there is no brand of steel made 
that will stand such treatment. There are now special gas 
stoves that may be used, and properly constructed muffles 
may also be erected and fed by the application of fine 
slack, which will do useful work in heating tools for harden- 
ing. Where neither of these are handy it is possible to 
heat a tool properly in a breeze fire, providing that the fire 
is large enough for the purpose, but it is useless trying to 
heat tools uniformly in a t-mall fire. First blow up a fairly 
large fire, then introduce the die, and, covering the die witn 
red-hot breeze, blow the fire very gently until the die has a 



264 MACHINES FOR SHEET METAL WORK. 

thorough gentle soaking. The greatest trouble with which 
the toolmaker has to contend in hardening his tools is th 3 
risk of their splitting, cracking, or warping. The cause of 
these troubles is generally the cooling and contraction of 
the various portions of the tool at different rates. To avoid 
this cracking and warping it is important that the tool be 
uniformly heated and as uniformly cooled as possible. In 
the case of dies, all screw, dowel, or gauge-pin holes in 
them should be filled with clay during the process of 
hardening. When quenching the tool plunge it straight 
down into the water, holding it stationary for a minute orso, 
then move it slowly about, keeping it perpendicular all the 
time. Do not use any of the to-catted special /tardeniny 
mixtures or fluid*, as they are practically worthless for tools. 
Use a plentiful supply of fresh clean water and brine, or rain 
water and brine, then, when you meet with a brand of steel 
that cannot be hardened by heating to a cherry-red and 
quenching in cold clean water, treat it as useless for tools 
and at once dispense with it. Tools such as drawing or 
extending dies, where the hole is required to be perfectly hard 
for its whole depth or length, the cooling of the central portion 
of the die may be assisted by directing a powerful jet of 
water through the hole in the die. An ordinary cutting-out 
bed or die is usually quenched by being plunged into a 
'* bosh " or tank filled with clean water and the die held 
under the water until it is quite cold, when it may be 
removed ; have its face cleaned or ground bright It may 
then be tempered by being placed upon a flat piece of red- 
hot iron. 

Very large dies may be heated for tempering either in a 
muffle or over a breeze fire. In all cases the slower and more 
uniformly the change of colour appears the more reliable 
will be the results from the tools. In tools for turning, 
planing, and shaping, chipping chisels, drills, and many 
varieties of press cutting-out punches, where it is not 
necessary to have the tool hardened for the whole of its 
length, the hardening (instead of being carried out by first 
jdnnginfj th*. whole tool into the water, holding it there until 
quite cold, then re-heating the whole tool for tempering) may be 
readily done at one heating. The following explanation of 



HARDENING AND TEMPERING AT ONE HEAT. 265 

hardening and tempering a chipping chisel will serve to 
illustrate how this is accomplished : 

The chisel, fig. 267, being held by its head II in a pair of 
tongs, is placed into the fire for about one-third its length 
A B, and carefully heated to a cherry-red, care being taken 
that the extreme end E of the chisel does not become over- 
heated. (If the chisel is very thin the end E should be 
cooled by dipping it into water once or twice during the time 
that the chisel is being heated.) After it has been heated to 
the required temperature it is dipped into the water for a 
portion of its length (according.to the size of the chisel this 
may vary from f in. to 1^ in.), and held in the water until 
cold ) then remove the chisel, and brighten the hardened 
portion C bv rubbing with a piece of stone or emery cloth. 
The heat will now travel from the unquenched portion to 
the quenched portion. The change of colour is watched as 
it travels along from B to A, until the required colour appears 
at the cutting end E, when the chisel is again plunged into 
the water bath ; this time the whole of it will be quenched. 
This method can be applied to any tools to be hardened at 
their ends only, but it must be understood that the nature 
of the work to be operated upon may necessitate the tool 
being brought down ia temperature to a totally different 
colour. For instance, turning tools, dark straw or yellow 
colour, 450 deg. temperature ; cutting-out punches for sheet 
steel, very dark straw or yellow, 490 deg. temperature ; cold 
chisel for chipping cast irou, dark purple colour, 550 deg. 
temperature. 

It should be noted that when chisels, drills, or turning 
tools are being forged, it is advisable to hammer them until 
the steel has become quite cold, as this hammering gives 
toughness and finene-s of texture ; it may then be re-heated 
for the purpose of hardening. Taps and reamers are some- 
times covered with a mixture of Castile soap and lampblack, 
to preserve their cutting edges, and to prevent them being 
burnt whilst being heated for hardening. This class of tools 
may also be heated in a wrought-irou pipe filled with charcoal 
dust, the ends being plugged with clay. This method 
generally results in the taps or reamers being heated uni- 
formly ; they are afterwards dipped into water in a vertical 
position, and held there until cold. 



266 



MACHINES FOR SHEET METAL WORK. 



Circular milling cutters may be covered with Castile soap 
aud lampblack with advantage, and the hole of the cutter 
plugged up with clay ; this preserves the centre, which is 
not usually required to be hard. The tools are generally 
slightly warmed before the mixture of Castile soap and 
lampblack is applied, and a circular cutter should be plunged 
into the water bath edgeways. The tempering of a tap or 
reamer is usually done by introducing it into a cast-iron or 
wrought-iron collar, which has been made red-hot ; the tool 
is held in a pair of tongs, and passed along the centre of the 



Q 



hole. At the same time it assists matters if the tool is 
rotated whilst being moved along, as the continual change 
of position prevents one portion becoming hotter than 
another, and results in a more even temper. Taps, reamers, 
milling cutters, and similar tools are generally tempered to 
a light brown colour, and quenched in oil 

Small piercing punches, say from ^ in. to i in. diameter, 
and dies from ^ in. to 1 in. diameter, are best heated in a 
wrought-iron pipe about 12 in. long and 2 in. diameter, with 
one end closed. This may be done by welding a wrougbt- 
iron plug in one end of the pipe (see fig. 262). The small 



HARDENING AND TEMPERING DIES AND PUNCHES. 267 

punches or dies are placed in the pipe, which is, in turn, 
thrust into the breeze fire. This method gives much better 
results than can be obtained when the flame of a fire is 
allowed to come in contact with such small tools. When 
the punches or beds, as the case may be, are sufficiently 
heated the pipe is removed from the fire, and the tools 
tipped into a bucket of clean water containing a handful of 



o 




common salt. Tools hardened in this manner will be found 
to be quite clean, and ready for tempering. This may be 
readily done by placing the tools upon a wrought-iron plate, 
say 12 in. square by ^in. thick, heated over a gas stove ; the 
small round punches would be rolled over the hot plate 
until the required colour appears, whilst small dies are best 
placed endways on the plate. In fig. 265 four punches and 
four dies are shown upon the plate, one of each being placed 



268 



MACHINES FOR SHEET META1, WORK. 



near the edge of the plate, as they are nearly ready to be 
pushed off the hot plate into a bucket of water. In the case 




Fio. 264. 



of the small die the heat travels up from the bottom, so that 
when the cutting end or face is a straw colour the back will 








<?- 



I i... 265. 



probably be blue ; but this will be an advantage, as it is only 
the cutting that is required very hard, whilst the effect of 
tempering the back of the die will help to preserve it. 



HARDENING AND TEMPERING A SLITTING SAW. 269" 

Small circular slitting saws for metal work may be 
hardened in the following manner : Referring to fig. 263, 
place the cast-iron planishing die D into a bosh of water B, 
filled to within about \ in. of the surface of the die. 
Arrange a second similar die D 1 , such as to allow of its 
being raised or lowered by a rope and pulley, in a somewhat 
similar manner to that by which a stamp hammer is actuated. 
By this means the top die may be brought down on to the 
die D. The saw, fig. 264, having been properly in a muffle, 
is now placed upon the die D, the top die D 1 is quickly 
lowered until its whole weight is resting upon the saw, the 
water is then thrown all round the edge of the die faces by 
the workman. The top die may now be raised and the 




tool removed. Saws that are hardened in this manner will 
be found to have their teeth perfectly hard, whilst being 
quite flat. 

These saws may be tempered by placing them upon a 
special casting (see fig. 266), heated in a muffle. The saw 
is placed upon the casting, and it is advisable to occasionally 
turn it over so that both sides may come in contact with the 
heated surface. The heat will travel from the centre of the 
saw to the teeth. 

Fig. 266 shows a saw in position ready for tempering, P 
being a plug cast on and roughly turned to enter the hole 



270 MACHINES FOR SHEET METAL WORK. 

of the saw very loosely ; the lug h forms a handle by which 
the casting is moTed about by a pair of tongs. 

In considering the subject of colour to which a tool should 
be tempered to give the best results, it should be remem- 
bered that different tool-steels may vary considerably. One 
brand of steel may require to be tempered to a brownish- 
yellow, whilst another to do the same work may have to be 
left harder. Another sample of steel may require to be 
taken much lower in tempering, to prevent the cutting edge 
of the tool from chipping. Then there is the question as to 
the metal the tool has to operate upon ; this will, to some 
considerable extent, govern the temper to be given to the 
tool. It will therefore be seen that it is hardly possible 



5 



to place on record any table that will be found to give 
reliable results with all steels. The following table, given 
by Professor R. H. Smith in his work on cutting tools, is 
very instructive and useful as a guide for tempering. If 
one has this table before him it is an easy matter to 
experiment with any particular steel to find out which is the 
most suitable temper for a certain operation. 

ANKEALIXG METAL. 

Sheet metals are usually purchased at the proper temper 
ready to be sheared or cut into blanks, but in drawing tubes 
or shells the action of the tools rapidly hardens the metal, 
thereby making it necessary to anneal the metal a number 
of times according to the number of operations or processes 
that the metal is passed through to produce the finished 
article. A cartridge case for a G in. quick-firing gun would 



ANNEALING SHEET METALS. 



271 



be 16 in. long, tapering from 7 in. diameter at the breech 
end to 6 '5 in. diameter at the muzzle end ; such a metal 
shell would be made from a blank 12|in. diameter by f in. 
thick and weighing 28| Ib. It is formed into the thin case 
or shell by successive drawings, annealings, pressings, and 



TABLE OF COLOURS FOR TEMPERING. 



Faint straw 



Brownish yellow 



Light purple .. 



Dark blue 



Scrapers for brass. 

Steel-engraving tools. 

Light-turning tools. 

Hammer faces. 

Planing tools for steel. 

Planing tools for iron. 

Paper-cutting knives. 

Wood-engraving tools. 

Flat drills. 

Milling cutters. 

Wire-drawing plates. 

Boring cutters. 

Screw-cutting dies. 

Leather-cutting dies. 

Taps. 

Chasers. 

Hock drills. 

Punches and dies. 

Reamers. 

Shear blades for metal. 

Gauges. 

Stone-cutting tools. 

Plane irons. 

Twist drills. 

Wood borers. 

Cold chisels for steel. 

Axes and adzes. 

Cold chisels for cast iron. 

Firmer or mortising chisels. 

Cold chisels for wrought iron. 

Circular saws for metal. 

Screwdrivers. 

Springs. 



squeezings, the weigbt when finished being 22lb. The 
number of operations, commencing by cutting out the blank 
and finishing by lacquering, is 32, including eight annealings 
and cleanings. As showing the necessity for properly 
annealing the metal, cartridge cases which have been manu- 
factured by firms of high repute have cracked through their 



272 MACHINES FOR SHEET METAL WORK. 

base spontaneously whilst they have been in the stores. 
This is supposed to be the result of the effort of the 
material to recover its normal state, and thus to have caused 
rupture.* 

The cause of these troubles has generally been traced to 
an insufficient number of operations in drawing and anneal- 
ing during the process of manufacture. It is probable that 
these troubles would not have happened had the cartridge 
cases been produced by a greater number of stages, thereby- 
bringing about the flow of the metal in a more gradual 
manner. Tn works where the ordinary commercial brass 
alloys are mixed and worked, and where the metal has to 
undergo severe torturing in the processes of rolling, drawing, 
and hammering, and where the general arrangements and 
number of annealing muffles are insufficient to deal properly 
with the amount of work done, the metal strip would be kept 
in the annealing muffle considerably longer, but at a much 
lower temperature than would be the case in ordinary 
annealing, thereby giving the metal what is known as a good 
soaking. The foregoing remarks, although directly concern- 
ing the manufacture of metal ammunition cases, teach a 
lesson with reference to sheet metal work generally, since it 
is certain that many of the troubles of cracking and splitting 
during the process of manufacturing sheet metal articles is 
due to the metal not having been properly annealed 
between the various stages of progress, and is further 
frequently caused by endeavouring to produce a difficult 
article with a stage or process less than should be given. 

ANNEALING DIES AND TOOLS. 

When dealing with cutting-dies, punches, stamping-dies, 
or any piece of steel which has to be worked or shaped by 
the action of cutting tools when in the cold state, previous 
to the tool being hardened, it is desirable that the steel be 
carefully annealed. Particularly is this necessary when 
stamp-dies of some peculiar and difficult shape have to be 
worked and finished in a first-class manner. When, a die 

See rental ks by Sir William Anderson, Proceedings, lust Mech. Engineer*, 
1897. 



ANNEALING DIES AND TOOLS IN SLAKED LIME. 273 

or punch, after having been forged, is thrown down upon the 
floor of a smith's shop to cool, thereby being exposed to cold 
air, especially in winter time, it frequently results in the 
steel being in an unequally hardened condition, which may 
also be partly caused by the hammering process. Annealing 
will generally remedy this defect, as the process of annealing 
reduces the steel to its softest and most uniform condition. 
The ease with which steel may be worked by the various 
cutting tools in a lathe, planing, milling, or drilling machines 
more than repays the little trouble that is necessary for 
annealing. Small articles such, for instance, as delicate 
tools, cutters, reamers, punches, and dies may be placed in 
an iron box, surrounded or buried in powdered charcoal ; the 
charcoal prevents the steel from losing its carbon and assists 
the uniform heating of these small tools, at the same time 
preserving their shape and preventing any damage being 
done to their cutting edges. After being heated the box is 
placed somewhere to gradually get cool before the small 
tools are removed. The larger tools can be successfully 
annealed by moderately and uniformly heating them in a 
muffle, then allowing them to cool slowly. This is some- 
times done by burying them in ashes to retard the cooling. 

The annealing is usually done before the forgings leave 
the blacksmith's shop, a good method being to carefully 
re-heat them after forging to a dull red and place them into 
an iron box containing slaked lime, where they should remain 
until cold, which frequently takes a whole day. They are 
then taken out of the lime, and will be found to be more 
easily worked into shape, and are not so likely to leave their 
shape when undergoing the hardening process. There are 
instances when dies and punches are annealed, roughed-out, 
and annealed a second time before being finally shaped to 
their finished outline with beneficial results. But this is not 
advisable if the tool can be readily worked fairly easy after 
one annealing, since too much heating may remove the 
nature from the steel. 



19\vp 



274 MACHINES FOR SHEET METAL WORK. 



CHAPTER XX. 
BLANK DIMENSIONS. 

THE three methods generally used to find the dimensions of 
a sheet metal blank are the tentative, the gravitative, and 
the mcnsurative probably, as a rule, more time is spent 
in experimenting to obtain the proper diameter of a blank 
than it takes to manufacture the tools. 

There are many experienced toolmakers who can design 
and manipulate the tools for producing almost any 
shaped article in a press that one cares to place before 
them, yet cannot form any idea by calculation as to what 
size blank is required from which the article is to be pro- 
duced. These mechanics usually work by the tentative 
method, either giving a rough guess based upon their past 
experience, and trying over and over again until they have 
arrived at the proper size or thereabouts, or they look over 
the patterns of previous work that has been done in the 
workshop, and select that blank which they think will work 
out approximately correct. 

The gravitative method is often used when a sample of 
the work to be done is supplied, and this method is par- 
ticularly useful in the case of stamping or raising sheet 
metal articles where no drawing or exltnding of the metal is to 
take place. The sample of work is carefully weighed and its 
thickness noted, after which a piece of sheet metal measuring 
one square inch in area and of the same gauge or thickness 
as the particular sample is also weighed. Then the weight 
of the sample or finished article, divided by the weight of 
the one square inch of sheet metal, will give the number of 
square inches to be contained in the blank for producing 
an article to sample. For example, suppose the toolmaker 
is supplid with a sample brass stamping which weighs 
(avoirdupois) 1 Ib. 4 oz. 6 drms. = 326 drms., and it is found 
that the weight of one square inch of sheet metal (measuring 
in thickness exactly the same gauge as sample) is Hdrms., 
then the number of square inches to be contained in the 



THREE METHODS FOR FIXING BLANK DIMENSIONS. 275 

Ofi)/ 

area of the required blank will be square inch = 217-333 

square inches. This will be the exact area of metal com 
tained in the sample, and assuming that the article is not 
to be clipped after being stamped, then a blank containing 
the 217'333 square inches would be correct. On the other 
hand, should it be necessary to clip the article after it has 
been stamped, as is frequently the case, then a few square 
inches must necessarily be added to the area of the blank, 
the amount added being according to the shape, size, and 
nature of the stamping. 

The mensurative method consists in finding the exact area 
that is contained in the surface of the article to be produced ; 
the blank is then cut out a certain size, so that it will 
contain the same area in square inches as the sample. The 
sample may be an actual finished article, or a sketch may be 
supplied showing the exact outline and size of the article to 
be made in either case it is a question of mensuration. 

Anyone having an elementary knowledge of mensuration 
of surfaces may, by exercising a little care and judgment, 
obtain fairly reliable results by means of finding the area of 
an article, and then fixing upon the proper diameter and 
shape for the required blank. But, even though a tool- 
maker may be able to deal with the mensuration of curved 
surfaces, it is not an easy matter to fix upon the diameter of 
a blank when dealing with articles which have to undergo a 
large number of processes, such as re-drawings or extensions, 
as, for instance, would be necessary in producing the brass 
cases for quick-firing ammunition. This is an instance where 
the pattern sample shelf often comes in useful to the tool- 
maker. 

It may be truly stated that the usual methods taught by 
mathematicians for obtaining the areas of curved surfaces of 
peculiar outline often introduce formula containing the 
differential and integral calculus. This makes it absolutely 
impossible for the practical mechanic or toolmaker to follow 
the reasoning necessary to work out the equations. When, 
however, such surfaces of unusual outline have to be 
measured, they may be readily dealt with in comparative 



276 



MACHINES FOR SHEET METAL WORK. 



ease .(if the article be measured up in sections). The few 
selected common shaped articles illustrated from fig. 268 
to fig. 280, together with their formula;, will enable the 
student to follow the application of mensuration to sheet 
metal processes. The examples have been reduced down to 



r 



H- - 2 - 

Fio. 268. 

ordinary figures, so that the working may be more readily 
followed by the practical mechanic in the workshop, who 
may, perhaps, not understand a simple algebraical equation. 
Some useful notes on mensuration of surfaces will be found 
in The Practical Engineer Pocket Book, besides tables of areas 




and circumferences of circles, squares and square roots, and 
decimal equivalents of fractional parts of an inch, all of which 
will greatly assist the workman to follow the examples. 
Fig. 268, Cylindrical flat-bottomed vessel : 



Area = * d h + 



= 3-1416 x 2 x 1 + 



4 x 3-1416 



= 9'4248 square inches, 
or 7r(2 + l)=37r = 9-4248 square inches. 



MENSURATION OF SHEET METAL SURFACES. 



277 



Then, to obtain the diameter of the required blank, multiply 
the square root of the area contained in the figure by 
1-12838. 

Thus the diameter of blank 



= x/9-4248 x 1-12838 
= 3'464 inches. 
Fig. 269, Cylindrical vessel spherical ended : 

Area = TT d h + 

= 3-1416 (2 x -75) -H 6-2832 

= 4-7124 + 6-2832 = 10-9956 square inches. 

Diameter of blank = ^10-9956 x 1-12838 
= 3-7416 inches. 




2 * 1 

Fio. 270. 

Fig. 270, Sphere : 
Area = d?Tr 

= 4 x 3-1416 = 12-5664 square inches. 

Diameter of blank '= v/12'5664 x 1-12838 = 4 inches. 
Fig. 271, Conical vessel : 

D + d o , d 2 IT 
Area = TT b + r 

when S = the slant height of vessel. 



278 MACHINES FOE SHEET METAL WORK 



The /A 1 + (E^Lf?)' will give the slant height S. 
The full equation will therefore be 



= 3-1416 6 . 2 5+l + 3-1416 

= 28-519 square inches. 




Diameter of blank = x/28'5l9 x M2838 
= 6-026 inches. 

The above method is approximately correct 

Another method of dealing with fig. 271 is to carefully 
set out the figure on paper, when the mean diameter at M M 
will be found to be 3 in., and the slant height to be 2-75 in., 
and the bottom of the vessel d being 2 in. diameter ; then 

Area = (3 x TT x 275) + ~ 

= 25-9182 + 3-1416 = 2906 square inches. 

Diameter of blank = N/29^06 x 1 -12838 

= 6-083 inches diameter. 



MENSURATION OF SHEET METAL SURFACES. 

Fig. 272, Elliptical flat-bottomed vessel : 

Area -- (circumference x h) + (area of bottom) 



Area = 



- (D + d) h TT D d 



T- JT 

(3-1416 x 5-5 x 1-25) 



(3-1416 x 7) 



= 10-79925 + 5-4978 = 16-297 square inches. 
Then an elliptical blank 3 -45 in. x 6 '03 7 in. will have its 
diameters in the same ratio as those in the vessel, fig. 272, 




52- 



FIG. 272. 

and will contain 16 '359 square inches, which is slightly 
larger than area actually required to be in the blank. 
Fig. 273, Kectangular vessel : 

Area = (x x y) + 2 (x x h} + 2 (y x h) 

= (3-5 x 2-5) + 2(3-5 x 1) + 2(2-5 x 1) 
= 8'75 + 7 + 5 = 20'75 square inches. 

Note. The length of sides of the rectangular blank must 
be in the same ratio as the sides of the vessel, fig. 273 ; so 
.that, since the sides of the vessel are 2 -5 in. and 3 -5 in., 
the sides of the rectangular blank will be 3 -86 to 5*404. 

Then 3-86 in. x 5-404 in. = 20-859 square inch. 



280 



MACHINES FOR SHEET METAL WORK. 



It will here be noticed that the area of the blank is sliu r litl y 
in excess of that of the example ; this size blank will, 
however, be sufficiently near for all practical purposes. 



, 



3f 



Fig. 274, Semi-oblate spheroid : A formula which gives 
the approximate area of a whole spheroid is as follows : 



Area 



X 



44-430 square inch. 



= ** *-- = 22-215 square inch. 
Therefore 22'215 square inch = area of semi-oblate spheroid. 




Fio. 274. 

Fig. 275, Cylindrical conical-topped vessel : 



MENSURATION OF SHEET METAL SURFACES. 



281 



S = slant height, and may be obtained in the same manner 
as was done in the case of fig. 271. 

The full equation for fig. 275 will therefore be 



Area 



d-Tr I (D + d) V /TT /D - c/'-Y 

-r( + 7r r^~i I i+ ( 2 ) 



= (9-081) + (5-105 x N / T 3906; 
12'26S square inches. 



t 



I I 

U_ 




The diameter of required blank = s/12'268 x 1-12838 
= 3-952 inches. 

flote. The 1 '12838 is a constant used to find diameters 
of blanks for all CYLINDRICAL vessels. 

Another method by which the area of fig. 275 may be 
found is 



Area = TT dh + (mean dia. of conical top x TT x S) + 



when 
and 



= belt of shell 
= bottom of shell, 



and mean diameter of conical top x TT x S = area of conical 
belt. 



282 



MACHINES FOR SHEET METAL WORK. 



Set out the conical top on paper, when the mean diameter 
at M M, fig. 275, will be found equal 1'625 in., and the slant 
height S equal to "625 in. 

The equation will 



Area 



Ttdh ++ (1-625 x 3-1416 x -625) 
12-271 square inch area. 



Fig. 276, Example of cylindrical stamping : The simplest 
way to measure this is to first lay out the outline of the 
figure on paper as shown, then treat each section of the 

[^ n ^ 




figure separately. It will be seen that the figure has been 
divided into six sections, and numbered 1st, 2nd, 3rd, 4th, 
f)th, and 6th. These divisions are bisected to obtain their 
mean diameters (see each section, rfj, </, </ 3 , d t , rf 8 , and </,). 

The area of each section should be now found by separate 
working, and all the six areas added finally together. The 
area of the bottom of the vessel is found, and adding this 
to the areas of the six sections, previously found, will give 
the approximate total area of the vessel. 

The semi-oblate spheroid may be treated in two sections, 
as will be seen at figs. 278 and 279. This enables the area 
to be obtained more accurately than by the formula) 



Area 



MEASURING AN ARTICLE IN SECTIONS. 283 

Fig. 277 shows the method by which the figure can be 
traced upon paper to enable the figure to be measured up in 
sections. This is done by an approximate method used for 
constructing an ellipse by means of arcs of circles. Draw 
the major and minor arcs, bisecting each other at right angles ;. 
draw the rectangle B E C; bisect B E at F ; draw C F and 
E D intersecting each other in G ; bisect C G by a line at 
right angles to it; the bisecting line meets the line CD in J, 
the centre from which the arc L C G is described. Complete 




Fio. 277. 

the quadrantal arc C L K, join K A, and produce to L, and 
join L J ; the point M is the centre from which the arc L A 
is described ; the ellipse can be completed by symmetry. 

Fig. 278 shows the one section, which is a slice cut off the 
top, and it will be seen that the ellipse or figure has been 
cut through at L G, thereby forming the spherical segment 
LCG. 

Area = 2 IT R h 

= 2 x 3-1416 x 2-4375 x -825 
= 9-572 square inches. 



284 



MACHINES FOR SHEET METAL WORK. 



Fig. 279 gives the remaining section or bottom half of the 
ellipse, in the form of a band or belt. The area of this ban'l 
= e x 2 ir a. First find e. 

e = length of the curve LA. 
_ number of degrees contained by L M A . 
860 



360 



of 2 x 3-H16 x 1-1875 = 1-015 inches. 




Flo. 279. 

Then area of band = 1-015 x 6-2832 x 1-876 
= 11-957 square inches. 

Therefore the area of semi-oblate spheroid 
= 9-572 + 11-957 
= 21-529 square inches. 



CLIPPING OF STAMPED AKTICLES. 285 

When stamping articles of irregular shape from sheet 
metals, such, for instance, as fluted cake pans, the 
work is usually stamped from a piece of sheet metal 
larger in area than what is actually required to form 
the finished article, the surplus metal being afterwards 
clipped off by special clipping tools made to suit the 
particular shape of the work. Further, as the work varies 
in shape and depth, so does the number of stamp blows and 




required number of annealings vary accordingly. But when 
raising articles in the power press, it is usual to make the 
blank the necessary area to simply form the required article. 
In such cases there will necessarily be provision made upon 
the top of the bottom die to ensure that an operator shall 
place the blank perfectly central upon the die, so that when 
the article is raised the raising shall be done evenly all round 
the circumference of the finished article. Such a pair of 
dies for raising are seen at fig. 280, where it will be noticed 



286 MACHINES FOR SHEET METAL WORK. 

that three bits of metal have been screwed down upon the 
top of the bottom die for the purpose of evenly adjusting 
the blank, as before explained. 



CHAPTER XXI. 
PRESSURES FOR CUTTING BLANKS. 

ALTHOUGH shearing and punching may be considered a true 
cutting action, it is of a rough character. It has been pre- 
viously explained that at times a punch and die is made flat, 
at other times concave or convex. 

When a punch is being forced through a metal plate, the 
first effect of the application of the punch is the crushing of 
the top surface of the plate within the circle of the hole 
about to be formed. The tendency of the punch is to draw 
or drag down the metal surrounding the punch. This 
dragging down of the metal is prevented by the bottom die, 
which supports the metal surrounding the punch. A certain 
amount of compression takes place, which varies according 
to the temper and thickness of the metal that is being 
operated upon, stresses are set up, and rupture occurs 
where the stresses have been greatest. When punching 
thin metals, the action is somewhat different to that of 
cutting the thicker metals. In the case of thin metal the 
action may be considered instantaneous, and the top edge of 
the hole in ' the scrap metal will appear to be perfectly 
square, whereas in the case of the thicker metals the 
shearing action is brought about in a more gradual manner, 
a series of successive ruptures taking place at various 
depths in the thickness of the metal plate, until the final 
shearing occurs. On this account it is difficult to say what 
actual force or stress is required to cut a given blank, unless 
experiments are made. But if the ultimate shearing 
strength of the metal is considered in the calculation, it is 
possible to arrive at approximate results that will meet all 
practical requirements. The shearing strength of cold 
rolled steel may be taken as 60,000 Ib. per square inch, 



PRESSURES REQUIRED TO SHEAR IRON BARS. 



287 



mild steel 50,000 lb., wrought iron 45,000 lb., and soft brass 
30,000 Ib. To simplify the calculations the above figures 
may be reduced to tons, so that to shear off wrought- 
iron bars 1 square inch area a pressure of 20 tons will 
be required at the punch. In a previous article some figures 
were given from Dr. Anderson's "Strength of Materials." 
Another interesting set of figures taken from the sam 
source will be found in the following table, which is a 
summary of some experiments relating to the shearing of 
wrought-iron bars. 



Size of bar in 
inches. 


Stress with bar 
laid flat upon its 
side, in tons per 
square inch. 


Stress with bar 
laid on edge, ia 
tons per square 
inch. 


Percentage of less 
stress required 
when detruted 
on flat surface. 


3 x Ik 


18-2 


20-1 


10 


4 X IS 


14-3 


17-9 


20 


3X1 


15-7 


21-1 


26 


5Jxl| 


16-7 


22-6 


26 


6 X 1J 


15 18-4 


18 



These experiments were made with shear blades at an 
inclination of 1 in 8. It will be noticed in the table that 
when the bar of iron was cut on the side or flatways the 
stress required was considerably less than when the iron bar 
was cut edgeways. This is doubtless due to the circum- 
stance of the work to be done being spread over a longer 
period, since in the case of placing the bar flatways upon the 
shear blade it only comes into action with a portion of the 
bar, due to the inclination of the shearing edge. 

To find the approximate pressure required to cut any 
blank, first measure up the area of metal to be sheared, 
then multiply by the shearing strength of the particular 
metal ; the result will be the pressure or stress required at 
the punch or at the ram. It will therefore be understood 
from the foregoing that the ultimate shearing strength of 
any metal may be used as a constant in any calculations 
respecting that pai'ticular metal. 



288 MACHINES FOR SHEET METAL WORK. 

Taking cold rolled steel, and the blanks to be cut as 
cylindrical, 

Let D = diameter of blank in inches, 

T = thickness of metal in inches, 
TT = 3-1416, 

C = a constant 26 '7 (for steel), 
P = pressure or stress required ; 
then P = DxTx:rxC. 

Example. What stress would be required to punch a 
blank 6 in. diameter through a steel plate | in. thick '? 

Here P = 6 x -375 x 3-1416 x 26'7 - 188-7 tons. 

Next suppose a set of shears has to cut off wro light-iron 
bars. 

Let W = width of bar in inches, 

T = thickness of bar in inches, 

C = a constant 20 (for iron), 

P = pressure or stress required ; 

then P = W x T x C. 

From this it will be seen that in punching a hole (not 
cylindrical) in a plate the section of metal in square inches to 
be sheared will be the circumference or length of the curve 
which forms the outline of the blank, multiplied by the 
thickness of the plate, the length of curve being obtained 
by the ordinary rules, according to the shape of the M.-uik. 
It then remains for this area to be multiplied by the 
constant C, which has been explained as that stress required 
to shear one square inch of metal. It must be clearly under- 
stood that these calculations refer to punching or shearing 
metals when the tools are quite flat that is, having no dip 
or shear. 

Further, it may be mentioned that when providing or 
designing a machine to perform punching or shearing of a 
blank or bar, it will be advisable to allow 6 as the factor of 
safety. In other words, assuming that the pressure required 
to punch out a blank has been arrived at by calculation, it 
will be necessary to provide a machine of such strength that 
it will require six times that pressure or stress to break any 



FACTOK OF SAFETY FOR SHEARING MACHINE. 289 

shafts or wheels that may happen to be used upon that 
machine. With reference to the example of cutting the 
cold rolled steel blank, 6 in. diameter by f in. thick, where 
a stress of 1SS'7 tons was required at the ram, it will be 
advisable to provide a machine having crank shaft and 
wheels of such strength that it would be necessary to intro- 
duce a resistance at the ram or tools equal to 188*7 x 6, or 
1,132-2 tons, before any portion of the wheels or shaft would 
break. The main casting or frame of the machine should 
necessarily be provided with the same factor of safety. 

The punching and shearing machine is an excellent 
example, demonstrating as it does the great value of the 
flywheel as a means of storing up energy that may be given 
out when required to cut a blank. In the case of a machine 
designed for cutting steel blanks 6 in. diameter by f in. 
thick, the weight of the flywheel was 15cwt., its diameter 
at the edge of the rim being 5 ft. The speed of the counter 
shaft carrying this flywheel was 116 revolutions per minute. 
A Bessemer steel crank shaft 6 in. diameter was provided for 
working the ram, the speed of the crank shaft being brought 
down to 25 revolutions per minute by means of spur 
gearing. 

According to Professor Goodman, it is usual to store 
energy in the flywheel equal to the work done in two 
working strokes of the shear or punch, amounting to about 
15 inch tons per square inch of metal sheared or punched 
through. 

DEFINITIONS. 

THE technical student aud practical mechanic will find the 
following definitions of terms assist him to a better under- 
standing of the problems concerned : 

The unit of work is the work done in lifting one pound 
through a height of one foot, or work done when a resistance 
of one pound is overcome through a space of one foot, and is 
called the foot-pound. 

Number of units of work performed = P x S where P 
equals the force applied, or the resistance overcome in 
pounds, aud S equals the space moved over in feet. 
20wp 



290 MACHINES FOR SHEET METAL WORK. 

Force is any action which can be expressed simply by 
\veight, and which can be realised only by an equal amount 
of reaction, and is the first element in dynamics. All bodies 
in nature possess the incessant virtue of attracting one 
another by gravitation, which action is recognised as force. 

Velocity is speed or rate of motion, and is the second 
element in dynamics. 

Time implies a continuous perception recognised as dura- 
tion, or that measured by a clock, and is the third element 
in dynamics. 

Power is the product of force and velocity that is to say, 
a force multiplied by the velocity with which it is acting is 
the power in operation. Power is the differential of work, or 
any action that produces work, whether mental or physical. 
Power multiplied by the time of action is work; work 
divided by time is power. 

Work is the product obtained by multiplying together 
the three simple elements force, velocity, and time. 

Energy of a body is its capacity for performing work. 

Potential energy, or the energy stored up, is the 
product of the effort and the distance through which it is 
capable of acting. 

Kinetic energy, or accumulated work of a moving body, 
is the product of the mass and half the square of its velocity, 
or the weight of the body multiplied by the height from 
which it must fall to gain its velocity. 

Gravity is the mutual tendency which all bodies of 
nature have to approach each other, or the tendency of any 
falling body to approach the centre of the earth. 

The mass of a body is its weight divided by 32 -2. 

The acceleration of motion is the rate of change in the 
velocity of a moving Ixxly, which is increased at different 
intervals of time. 

The unit of acceleration is that which imparts unit 
change of velocity to a moving body in unit time, or an 
acceleration of one foot per second in one second. 



THE POWER OF PRESSES AND STAMPS. 291 

The acceleration due to gravity varies at different 
places on the earth's surface. In this country it is reckoned 
at 32 '2 feet per second, and is generally indicated by the 
symbol g. 

Retarded motion : The motion of a body, instead of 
being accelerated, may be retarded that is, its velocity may 
decrease at different intervals of time. 

Varied motion is usually understood to refer to a moving 
body, when the change varies in either accelerated or retarded 
motion, at different intervals of time. 

Vis-viva is the energy of a moving body measured by 
the distance it will pass over before being brought to rest by 
a resistance of uniform intensity. It is proportional to 
mass x (velocity) 2 . 

Inertia is that quality inherent in matter whereby it is 
absolutely passive or indifferent to a state of rest or motion. 

A couple consists of two parallel forces which are equal, 
and act in opposite directions. 

Weight of a body is the pressure which the mutual 
attraction of the earth and the body causes that body to 
exert on another with which it is in contact mass multiplied 
by 32-2. 

Linear Velocity is the rate of motion in a straight line, 
and is measured in feet per second, or per minute, or in 
miles per hour. 



THE POWER OF PRESSES AND STAMPS. 
WHEN considering the power required to perform work in 
either a press or stamp difficulties arise under the usual 
working conditions which make- it impossible to obtain 
reliable results by any known formula. One reason for this 
is that the effect at the face of the hammer, or at the point 
of the punch, as the case may be, depends so much upon 
the nature of the resistance, the result being that it renders 
the ordinary formula unreliable, so far as practical workshop 
operations are concerned. In a previous article attention 
has been drawn to the fact that when punching or shearing 



292 MACHINES FOB SHEET METAL WORK. 

metals approximate results, which are governed by the 
ultimate shearing strength of the metal, may be obtained. 

As a rule some ordinary formula would be used to 
calculate the work stored up in a fly press or stamp hammer, 
after which a rough estimate of the resistance offered 
according to the nature of the material, its thickness, and 
the time taken to perform the work would be obtained. 
In works where a large number of presses or stamps are 
used it is usual to carry out a series of experiments to find 
the amount of work that can be done in a certain press, 
having a screw of known pitch, a fly lever of a certain 
length, and by placing balls of different weights upon this 
lever. Again, experiments are frequently carried out to 
enable some idea to be formed as to the amount of work 
that can be done by a certain weight of hammer falling 
through a given height, and in this way approximate data 
may be obtained which will greatly assist in estimating what 
size machine would be required to make some specific 
metal article. By working out a few examples it will be 
instructive to see how these unknown quantities are con- 
tinually having to be assumed when dealing with problems 
connected with the press and stamp ; at the same time the 
working out of these problems will enable one to obtain 
some approximate results by the principle of work. 

WORK IN THE COPYING PRESS. 

The screw-press, fig. 281, is used extensively for copying 
letters. It consists of a frame D, bored and screw-cut to 
form a nut to receive the square-threaded screw S, an iron 
slab E connected to one end of the screw, and a lever handle 
ACB fixed to the other end. In operating the press a 
couple comes into action which rotates the screw. The 
relation of P to W may be found as follows : Let P equal 
the push applied at the end A, and also the pull applied at 
the end B, of the lever handle, and W the resistance over- 
come i.e. t the pressure that can be put upon any object 
and let p equal the pitch of the screw thread. 
Work of W per revolution = W p 
Motion of P per revolution = 2 ir r 



WORK IN THE COPYING PRESS. 295 

Then from the principle of work we have in one revolu- 
tion (the power applied being 2 P) 



or 



P : W : : p : 4 TT r. 



Example, In the screw press, fig. 281, the lever handle 
is 16 in. long, P is 20 Ib. at each end of the lever, and the 
pitch of the screw is ^ in. Find the pressure that can be 
obtained at the slab E. 





The distance travelled by 2 P in one revolution = 2x16 
TT inches, and distance moved by W = ^ in. 
Then 



w.i ^_ 

From the equation 



16?r 



8042-49 Ib. pressure. 



P 

lirr 



294 MACHINES FOR SHEET METAL WORK. 

it is evident that any of the unknown terms may be found 
when the other three terms are given. 

The work done by the screw-jack when used for lifting 
weights may be treated in the same manner as the screw 
press. 

WORK OF FLY PRESS. 

By reviewing the action of the fly press, it will be 
interesting to see how the work accumulated in a moving 
body is applied to overcome the resistance offered when 
punching holes in metal plates. In this machine, fig. 282, 
a screw S of rapid pitch is attached to the fly lever F, 
which terminates at two massive cast-iron balls B, B l , and 
on the lever is welded a rod E ending in a handle H. The 
operator exerts a certain pull " quantity unknown " upon 
the handle, which transmits motion to the fly lever F, and 
gives considerable velocity "quantity unknown" to the 
two balls, thereby causing work to be accumulated, this 
energy being available when required to punch the metal M. 
"When calculating the work that can be performed in a 
fly press, neither the pitch of the screw, the length of the 
lever, or the pull applied at the handle are considered in 
the question." The screw is made of rapid pitch for several 
reasons, the two principal being First, to enable the 
operator to raise or lower the punch P quickly by a small 
movement of the handle H, thereby allowing the various 
thicknesses of metal plate, or depth of articles, to be placed 
between the tools ; also enabling the punch P to be raised 
up to the stripper S, F, without necessitating much move- 
ment of the operator. Second, the rapid pitch of screw 
assists the operator in giving velocity to the balls, and at 
same time the velocity is maintained. The effect of the 
descending weights of the balls is, however, disregarded 
when calculating the power of the fly press. 

The work available for overcoming the resistance offered 
by the metal plate is that which is accumulated in the 
heavy balls B, B l at the moment of impact. Let the 
resistance of the plate (which is supposed to be a constant 
or uniform resistance throughout its whole thicknew), be 
denoted by R, let W be the combined weight of the two 



THE WORK OF A SCREW PRESS. 295 

balls, v the velocity of the balls at the moment of impact, 
and let y feet equal the distance through which the resist- 
ance is overcome i.e., y feet equal the thickness of metal 
plate. The accumulated work in the balls 
W v 2 



also the work of the resistance = R y, and by the principle 
of work 

W v 2 



therefore ^ W 

1 = - 



igy 

Example. Two balls, each weighing 30 lb., are placed at 
the ends of a horizontal fly lever 3 ft. long from centre to 
centre of the balls The lever imparts motion to a vertical 
screw of 2 in. pitch. What resistance will the punch over- 
come, if the balls have a velocity of 30 ft. per second at the 
moment of impact, and the punch is brought to rest after 
traversing a distance of T Vth of an inch ; also what energy is 
stored up in the balls. 
Accumulated work or energy in balls 
W 30 x 2 , 20 x 20 



2g 2 x 32-2 

This 372 -6 7 foot-pounds will be absorbed in punching the 
Y^th inch plate, or through a space of T V x IT = 
1 "ft. ; therefore 

30 x 2 x 20 x 20 
: - - 



64-4 x 1 

.-. 53664-59 lb. is the mean resistance to the puuch, 
when brought to rest in a space of ^th of an inch. 

FLY PRESS COMPARED WITH COPYING PRHSS. 
Now let us see why the massive cast-iron balls are used 
upon the fly lever of a screw press. In the case of the 
copying press a certain pressure is applied to the letter 



296 MACHINES FOR SHEET METAL WORK. 

book so long as the hands are exerting the pull and the 
push by working with a comparatively fine-pitch screw 
and a lever worked bv both hands, and, where this lever 
has to be moved through the circumference of the circle 
described by P, several revolutions before the actual 
pressure is applied to the letter book ; whereas the fly press 
has to be worked uuder entirely different conditions. The 
screw must necessarily be of rapid pitch, so that by the 
slight movement of the fly-lever handle, which is grasped 
by the operator's one hand, the punch may be quickly 
raised or lowered, leaving the operator's left-hand tree to 
feed the metal articles on to the tools. 

Suppose, for example, that the fly press, fig. 282, has a 
lever handle H, upon which the operator exerts a pull of 
50 lb., the radius of circle described by the handle H is 
15 in., and the pitch of the screw is 2 in. Find the pressure 
applied at the punch P. 

Here the pressure 

= 50x 2 27rr = 2356-2 lb. 

In cutting-out or punching blanks, raising, drawing, and 
similar work in the fly press, the distance y feet through 
which the resistance is offered varies considerably, and the 
nature of this resistance is such that a continual pressure is 
required at the punch during the whole time that the work 
is being performed. The pressure of 2356-211). which has 
been found by calculation, though useful for copying letters, 
would be absolutely useless in the fly press for punching 
holes through metal plate unless the work was indeed very 
light Further, an operator could not exert a pull of 50 lb. 
at the lever handle H for very long, without becoming 
thoroughly exhausted, thereby loosing all his available 
energy, probably over cutting one thin blank. 

Suppose the fly press is punching holes 1 in. diameter 
through a steel plate 3 in. thickness. By the shearing and 
punching formula we have 

P = DxTxTxC; 

P = 1 x -125 x 3-1416 x 26-7 
= 10-485 tons = 23486-4 lb. 



FLY PRESS COMPARED WITH COPYING PRESS. 



297 



Here is therefore a resistance of 23486 '4 Ib. offered by the 
steel plate whilst the 1 in. hole is being punched, and the screw- 
press calculation only resulted in a pressure of 2356 '2 Ib. 
Now, placing two balls upon the fly lever, each ball weighing 
30 Ib., considerably alters the conditions. The operator 
pushes the fly handle as far back as possible ; theu, when he 
comes to pull the handle H, the velocity attained by his 




FIG. 282. 



hand is very great, and at the moment or instant of impact 
the operator throws the upper portion of his body back by a 
quick movement, thereby considerably increasing the velocity 
of the balls. The screw and the lever have greatly assisted 
him to attain the high velocity, but the energy given out by 
him has been accumulated in the balls, which in the previous 



298 MACHINES FOR SHEET METAL WORK. 

example works out at 53664-59 Ib. at the punch, when the 
velocity was assumed to be 20 ft. per second. 

By adding to the fly press the two cast-iron balls, the 
accumulated work is 372 '67 foot-pounds, which enables the 
fly press to overcome a resistance of 53664 '59 Ib. at the 
punch. 

The fact of adding the balls has made available over 
double the energy that is actually required to deal with the 
work the machine has in hand. 

WORK. DONE BY STAMP HAMMER. 

The great value of the stamp was mentioned in a previous 
article, and attention was drawn to its simplicity and cheap- 
ness as a means of storing energy, which could be given 
out again in doing the work of raising, stamping, and 
forging. 

The stamp hammer is an example of the useful application 
of the principle of the falling weight. In finding the work 
accumulated in any moving bod}-, such, for instance, as 
energy stored up in a flywheel, the work of a railway engine 
when ascending an incline, the work of a cannon ball, and 
similar questions, it is necessary to introduce the force of 
gravity into the calculation, since the law of gravitation 
necessarily has an effect upon such bodies as are dealt with 
in these calculations. It is therefore perhaps necessary to 
briefly review the action of gravity on falling bodies to enable 
the practical mechanic to understand what // means. 

If a body be raised 16 t V ft., then allowed to fall freely, it 
will fall through this space of 16 /TV ft. in one second, and at 
the end of that second it will have attained a velocity of 
32Jft. per second. This velocity of 32^ ft per second, 
which is simply due to the force of gravity, is denoted by g, 
and the velocity v attained at the end of t seconds will be 
t x 32|, or v = t x 32 J, Therefore the velocity of a body 
which has fallen for four seconds will lie at the end of that 
time travelling at a velocity = 4 x 32 = 128| ft per 
second. 

The mean velocity that is, the velocity in the middle 
of that time will be" 2 x 32 J = 64* ft per second, and the 
space described will be 4 2 x 



WORK DONE BY A STAMP HAMMEB. 299 

FORMULA FOR FALLING BODIES WHEN FALLING FROM REST. 
h = height of fall in feet. 
v = velocity in feet per second. 
g = force of gravity = 3 2 '2. 
t = time of fall in seconds. 




If the stamp hammer be raised to a definite height, the 
work expended in raising it will be W x h, and in doing so 
the force of gravity will have to be overcome. If the 
hammer be now supported, there will be "potential energy" 
stored up in it, and when allowed to fall it will attain a 
certain velocity depending upon the distance fallen. When 
the hammer reaches the end of its fall, the accumulated 
work in the hammer will be 

WV 



and w * 2 -w h 

'*g 

Example. Suppose a stamp hammer of 500 Ib. weight 
be raised through a height of 579 ft. The work expended in 
raising this hammer will be 

W x h = 500 x 579 = 289500 foot-pounds. 

If the hammer be now supported at this height, the 
potential energy which exists in, or is stored up, will be 
= 289,500 foot-pounds. When allowed to fall the accumu- 
lated work will be 



First find v: 

v = JTli = N/2~x 32 \- x o79 = 193 ft. per second ; 



300 MACHINES FOR SHEET METAL WORK. 

,'. when the hammer reaches the end of its fall it will have 
attained a velocity = 193 ft. per second ; 

w = ^r^m - 28950 foot - pound8 ' 

and this is the same result as W x h. 

A certain amount of energy is passed into the stamp 
hammer in raising it up, and when it falls the energy is 
given out again. There is neither gain nor loss of power. It 
may be that a great pressure is exerted through a small 
space, or a less pressure exerted through a greater space, 
and in both instances the work may be the same. 

If a resistance is offered to a 560 Ib. hammer, falling 
from a height of 16 ft, during the last one foot of its fall 
the average pressure acting against the resistance will be 
8,960 Ib., the pressure being much greater at the commence- 
ment, and reducing as it reaches the last inch; i.e, (this 
reasoning applies to the last 12 in. of a fall of 16ft.), the 
accumulated energy gradually decreasing to simply that of 
the weight of the hammer itself as it reaches the end. 

But should the hammer be brought to rest in a fraction of 
1 ft, then the resistance offered must be proportionally 
greater. 

A stamp hammer 200 Ib. weight falls 10ft, and in 
stamping a piece of metal the hammer is brought to rest in 
the space of the last in. in its fall. What resistance has 
been offered by the metal article 1 

W x h = 200 x 10 = 2000 foot-pounds, 

^ in. 
and since 




Notwithstanding the fact that the work of a stamp 
hammer may be calculated without considering gravity, we 
will now consider the case of another kind of hammer, 



ACCUMULATED ENERGY STORED IN HAMMER 301 

which is assisted by the workman's arm the hand hammer. 
The conditions under which the hand hammer is used make 
it necessary that the law of gravitation shall be introduced 
into the calculation. Take the case of a fitter striking a 
blow upon the head of a chisel, or driving a nail into a piece 
of wood, with a 2 Ib. hand hammer. 

As another example, consider the case of a fitter driving a 
key into the boss of a flywheel with a 4 Ib. jack hammer. 
In the first case there are two forces acting upon the 
hammer, namely, force of gravity and the man's muscular 
force. The workman raises the hammer ; he then drives it 
home, delivering a blow upon the head of the chisel. The 
first portion of the distance through which the hammer 
moves is traversed by a movement of the whole arm from 
the shoulder. 

This is followed up by the workman straightening his 
arm at the elbow ; then, just as he is about to reach the 
head of the chisel with the hammer to strike the blow, 
he straightens his wrist, thereby adding impetus to the 
hammer, which is already rapidly falling, and in this manner 
a very great velocity is given ; probably at the exact moment 
of impact the actual velocity may be 50 ft. per second. 

In the second example, where a blow is delivered upon 
the head of a steel key by a jack hammer, and the hammer 
is driven in a horizontal line, the fitter will swing the 
hammer through a comparatively long distance, and will 
probably put the weight of the upper half of his body into 
the blow, thereby considerably increasing the velocity of the 
hammer, which may be 50 ft, per second, as before. In both 
these cases of hand hammers the accumulated work or energy 
stored up in the hammer will be the same as though the 
hammer had fallen from a sufficient height to attain that 
velocity which the hammer has at the moment of impact. 
But here the only information we have to assist us in solving 
the problem is the weight of the hammer and the assumed 
velocity at which it is moving, say 50 ft. per second. Since 
having no particulars as to the height from which a body 
must fall to attain this velocity, it is necessary to introduce 
the law of gravitation into the calculation to enable reliable 
results to be obtained. 



302 MACHINES FOR SHEET METAL WORK. 

Here we have for the 2 Ib. hammer accumulated work 
W v 2 - 2 x 50 x 50 _ ft - 4 
1, 2x32 = '8 foot-pounds. 

If the face of the hammer moves the head of the chisel 
T V in., then 

rV * A - T^T of 1 ft ; 
. R= 78_xJ92 = U9761b 

If a nail had been driven \ in., 

i x ^ = -jig. of 1 ft. ; 



= 37441b . 



In the case of the 4 Ib. jack hammer we have accumulated 
work 



4 x 50 x 50 , KC , 4 

2 - Q^ 156 foot-pounds. 

If the key is driven in. by the blow, 

i x iV = A of 1 ft. ; 
156 x 96 



149<6 Ib. resistance. 



The work done by the jack hammer, namely, 1 4,976 Ib., 
is approximately the same that would be obtained by a dead 
load of 14,976 Ib. giving a direct pressure. 



INDEX. 



Accidents to Operators' Fingers 193 

Accidents to Stamp Operators 



Acting, Single, Press, Chief Defects in 

Action, Double, Press Construction 

Action of Punching and Shearing 

Accumulated Energy Stored in Hammer. 

Accuracy and Durability 

Accurate Methods of Drilling by Jig 



243 



. 
Accurate Boring Jig, Preparation of ........................................ 249 

Accurately Boring Tools and Jigs .......................................... 241 

Adjusting Ram by Means of Plates ...... . ................................. 42 

Adjusting the Pressure Plate .............................................. 165 

Adjusting Double Crank Press ....................... '. .................. 107 

Adjustment, Worm, for Ram .............................................. 197 

Advantage of Balanced Slides .............................................. 167 

Advantages of the Double Stamp .......................................... 206 

Advantages of Roller-feed Motion .......................................... 183 

Alloy Suitable for Cartridge Cases .......................................... 3 

Angle of Dip on Shears .................................................... l>4 

Angle on Punch for Cutting ................................................ 65 

Annealing Dies in Slaked Lime ............................................ 273 

Annealing Sheet Metals .................................................... 271 

Application of Roller-feed Motions ......... . ............................ 191 

Armature Disc-notching Machine .......................................... 201 

Attaching Punches, Methods of ............................................ 09 

Attaching Punches in Double-action Press .................................. 145 

Automatic Drop Hammer ................................... ............... 209 

Automatic Drop Hammer, Details of ..................................... 211 

Automatic Knockout or Flipper .......................................... 97 

Automatic Umbrella Stretcher Machine .................................... 103 

Automatics and Machine Tools .......................................... 215 



B 

Back, Open, Single-acting Press 161 

Balanced Slides, Advantage of 167 

Bed, Cutting-out being Profiled 231 

Bed Cutting, Guide Plate Fixed to a 261 

'. 259 
. 121 
. 123 



Bed, Punch and Stripper, Correct Setting 

Bed, The Stop Peg on a Cutting 

Bunding Tools for Wire 

Bending Tools for Metal, Form of 

Best Dipping Metal 

Blank Dimensions 27< 

Blank Feeding by Vertical Hopi>er 20! 

Blank Cutting by the Shearing Method ! 



304 INDEX. 

Blank Cutting Tools, Set of us 

Blanking, Successive Piercing and 187 

Blanks, Pressure Required to Cut 287 

Blanks, Shea ' 
Block, Stami 



Blanks, Shearing Circular 179 

Block, Stamp, Weight of .. 205 

Bolster, Method* of Fixing 75 



Bolt, Stay, The Use of a, on a Press ........................................ 153 

Boring a Stamp Die on Lathe ............................................. 219 

an Accurate ................................... 249 

241 
7 



orng a amp e on ae 
Boring Jig, Preparation of an Acc 
Boring Tools and Jigs Accurately 
Brown and Sharp Micrometer 



c 

Careless Hardening ............... , . . 57 

Careless Tool Setting, Trouble Caused by .................................... 253 

Cast-iron Driving Clutch .................................................. 44 

Cartridge Shell, Formation of .............................................. 136 

Changing Tools in Double-ended Press ...................................... 169 

Chief Defects in Single-acting Press ........................................ 159 

Chuck, Special Form of Drill .............................................. 101 

Chuck, Special Form of Work .............................................. 116 

Circular Blank Shearing .................................................. 179 

Clipping of Stamped Articles .............................................. 286 

Combination Tools ........................................................ 141 

Common Sheet Brass ...................................................... 3 

Common Stripper Arrangements and Waste Work .......................... S66 

Compared, Parallel and Screwed Shauk ................................... 78 

Complete Set of Piercing Tools ............................................ 93 

Complete Set of Blanking Tools ............................................ 98 

Concerning the Dial-feed Plate ............................................ 189 

Construction of Cropping Die .............................................. 105 

Construction of Dial-feed Motion ......................................... 185 

Construction of Double-action Press ........................................ 143 

Construction, Important Points in Press .................................... 151 

Copying Press. Work Done in a ............................................ 292 

Correct Setting of Punch, Bed, and Stripper ................................ 257 

Correct Tool Setting, Necessity of .......................................... 251 

Correcting the Die ....................................................... 83 

Coupling Two Crank Shafts ................................................ 52 

Crank, Double. Press ...................................................... 197 

Cropping-die Construction ................................................ 105 

Cutting Angle on Punch .................................................. (55 

Cutting Bed, Guide Plate Fixed to .......................................... 261 

Cutting Bed, The Stop Peg on a ............................................ 269 

Cutting Blanks by the Shearing Method .................................... 181 

Cutting Screw on Punch Shank ............................................ 291 

Cutting-out Bed being Profiled .......................................... 231 

Cup, Spinning a Sheet Steel ................................................ 113 

Cylindrical Die, Methods of Fixing ........................................ 77 

D 

Dangers of Sliding-key Stop Motion ..... ................................... 175 

Defects, Chief, in Single-acting Press ...................................... 169 

Details of Metal Shearing Machines ........................................ 177 

Descentof Ram, Unexpected .............................................. 195 

Details of Dial-feed Motion ............................................... 187 

Details of Power Press .................................................... 41 

Detailsof Screw Press .................................................... 24 

Dial Plate, Important Points Concerning .................................. 189 

Dial-feed Motion, Construction of .......................................... 185 



INDEX. 305 

Dial-feed Motion, Details of ..................................... . f^g* 

Die and Punch, Intel-changeability of ..................................... j 79 

Die, Boring on Lathe for Stamp . ....................................... \ 21!) 

Die, Correcting the ...................................................... [. 83 

Die, Cropping, Construction of ..................................... ]05 

Die, Cylindrical, Methods of Fixing ........................... 

Die Making by Drift ................................. ' 87 

Die, Method of Drilling a Cutting .......................................... 227 

Die Preparing for Drifting .............................................. ' . 91 

Die, Preparing a Standard .................................................. 81 

Die with Wrought-iroii Base ............................................... 58 

Dies and Punches, Hardening and Tempering .............................. 267 

Dies and Punches, Standard ................................................ 80 

Dies, Annealing, in Slaked Lime .......................................... 273 

Dimensions of Blanks ...................................................... 274 

Dimensions of Tools for Re-drawing ........................................ 131 

Dip on Shears ........................................................... 64 

Direction of Shaft Rotation ................................................ 49 

Disc-notching Machine for Armatures ...................................... 201 

Dividing Head Stocks, Quadrant ............................................ 235 

Double-action Press, Attaching Punches in .............................. 145 

Double-action Press, Construction of ........................................ 143 

Double-crank Press, Adjusting ............................................ 197 

Drawing a Metal Sphere .................................................... 133 

Drawing and Re-drawing .................................................. 127 



Drawing Press, Toggle 

Drawing Punch End, Radius on 

Drawing Punch, Removing Small Shell from 



ing 
. For 



Drift. Formation of the 

Drifting, Preparing the Die for 

Drilling a Cutting Die, Method of 

Drilling by Jig, Accurate Methods of 

Drill Chuck, Special Form of 

Drilling Machine for General Purpose 
Driving Countershaft by Pin Clutch. . 

Drop Hammer, Automatic 

Drop Hammer, Automatic, Details of 
Durability and Accuracy 



E 

End Radius on Drawing Punch 129 

Energy Accumulated and Stored in Hammer 301 

Example of Double-sided Fly Press 2J 

Example of Power Press 

Examples of Cylindrical and Rectangular Dies 5i 

Examples of Spinning Operations 107 

Extracting Mechanism Actuated by Ram 117 

Extracting Mechanism, Setting the 119 

F 

Face Plate, Setting Work on a Lathe 245 

Factor of Safety f< >r Shearing Machine - t! 

Faults Due to Pitch of Screw 81 

Faults in Construction * 

Faults of Cart-iron Driving Clutch 

Faulty Method of Driving the Ram 

Feed Motion, Advantages of Roller J 

Feed Motion, Construction of Dial J 

Feed Motion, Details of Dial J f' 

Feed Motions, Application of Roller *.'' 

Feeding Blanks by Vertical Hopper -" 

21wp 



Fixing Blank Him, n-i..i 

Fixing Bolster, Methyls of 

Fixing Cylindrical Die, Methods of 
Fixing Punch, Methods of . . . 



Fly Press Compared with Copying Press 

" Force " or Top Stamp Die 



306 INDEX. 

PAOB 

Fingers, Accidents to Operators' 193 

- ... m 

... 75 
... 77 
... 09 
... 297 

Top Stamp Die 59 

Forces Acting on Ram 51 

Forging a Stamp Die 54 

... 135 
... 27 
... 89 
... 121 
... 123 
... 45 
... 31 
... 31 
... 213 



r . .ruction of Cartridge Shell 

Formation of Gartering Nut 

Formation of the Drift 



Formation of Tools for Bending Wire 
Formation of Tools for Bending Metal 
Four Hams Operated Simultaneously 

% Frame Casting Screw Cut 

* Frame Casting Bored for Separate Nut 
Friction, Stamp Raised by 



G 

Gartering the Ram ........................................................ 28 

Gear for Belt Driving ...................................................... 40 

Graduations on Micrometer Thimble ...................................... s 

Guide and Stripper Plates .................................................. 05 

Guide Plate Fixed to Cutting Bed .......................................... 261 

H 

Hammer, Accumulated Energy Stored in .................................. 301 

Hammer, Automatic Drop ................................................. 20!' 

Hammer, Automatic Drop, Details ........................................ 211 

Hammer, Stamp Raided by Friction ........................................ '-'I:: 

Hammer Stamp, Weight of, and Block ..................................... 205 

Hammer Stamp. Work Done by .......................................... *.>'J> 

Hardening and Teni]>ering a Sl'itting Saw .......... ..................... 26H 

Hardening and Temju-ring Dies and Punches ............................... 867 

Hardening and Tempering atone Heat .................................... -<'> 

Han loning Careless ........................................................ 57 

Head, Spinning Rivet ................................................... Ill 

Headstocks, Quadrant Dividing ........................................ 2X5 

Heating Steel Uniformly for Hardening .................................... 2W 

r, Vertical, for Feeding Blanks ...................................... 203 



I 
Imperial Standard Wire Gauge ............................................ 14 

Imimrtaut Points in Press Construction .................................... I'd 

Important Point- Concerning Dial-feed Plate ............................. 1S'. 

Indicators, Methods of Applying Test ...................................... 2:;9 

Indicators, Types of Test .................................................. 2*7 

Interchangeable M.u-hine Parts ........................................... 246 

Interclumgeable T.H.ls ............................ ....................... 

Intel-changeability of Die and Punch ...................................... 7;> 

Internal and External Gauges .............................................. 10 

Iron Bora, Pressures Required to Cut ................................. 

J 

Jig, Accurate Methods of Drilling by ..................................... _> 

Jig Boring, Preparation of an Accurate .................................... 89 

Jigs and Tools for Rci-et it ion Work ........................................ 2.W 

Jig* and Tools, Accunitelv Boring .......................................... 241 



INDEX. 307 

K PAGE 

Key for Gartering Bolt 29 

K, \-->li ( ling, Dangers of, Stop Motion " 175 

Knockout or Automatic Flipper 97 

L 

Lathe Face-plate, Setting Work upon a ... 245 

Lathe for Boring a Stamp Die 219 

Lathe Test Indicators '. ..'.'.'.'. 237 

Lathe-spinning 110 

Lift, Positive, or Pressure Plate 163 

Limit of Thickness that may be Punched P3 

Limits of Accuracy 18 

M 

Machine, Drilling, for General Purpose 225 

Machine for Notching Armature DISCS 201 

Machine for Shearing Circular Blanks 179 

Machine Parts. Interchangeable 246 

Machine Profiling, the Use of 229 



Machine 



Machi 

Machine 

Machi 

Machi 



Shearing, Factor of Safety 

the Use of Shaping 223 

.tics . . , 



! Tools and Automatics 215 

Umbrella Stretcher 103 

Vice, a Special 233 

Machines used for Tool Making 217 

Measuring an Article in Sections '-'83 

Mechanism-extracting Actuated by Ram 117 

Mechanism-extracting, Setting the 119 

Mensuration of Sheet-metal Surfaces 277 

Metal Bending Tools 123 

Metal Gauge Tables 4 

Metal Shearing Machine, Details of 177 

Metal Sphere, Drawing a 13! 

Metal Spinning 106 

Metal Work Defined 1 

Method of Cutting Blanks by Shearing 1SI 

Method of Drilling a Cutting Die 227 

Method of Strengthening Press Frame 89 

Methods of Applying Test Indicators 23i 

Methods of Attaching Force to Stamp Hammer 58 

Methods of Drilling Accurately by Jig 243 

Methods of Fixing Blank Dimensions 27- 

Methods of Fixing Bolster 75 

Methods of Fixing Cylindrical Die 77 

Methods of Fixing Punch t> ! 

Micrometer Reading ' 

Micrometer Rolling Mill Gauge 12 

Motion, Advantages of Roller-feed 183 

Motion, Application of Roller-feed 1 ] 

Motion, Construction of Dial-feed 18; 

Motion, Details of Dial-feed I 8 ' 

Motion, Stop, Arranged in Ram 171 

Motion, Stop, Dangers of Sliding-key ^ 5 

Motion, Stop, Proper Place to Apply the 1 ' ; 

Multiple-threaded Screws d 

N 

Necessity of Correct Tool Setting 25! 

Notching Armature Discs -< 



308 INDEX. 

o 

old Biiiningham Wire Gauge .; 

in,,, ll.-at Hardening and Tempering 2f.i 

- ' 

21 

107 

-JOS 

, ll3 

204 



kicked Press, Single-acting ... 
Mirations Defined by Terms ........ 

i ijvrations of Metal Spinning ........ 

( Iterators, Accidents t Stamp 

* 



Fingers, Accidents to 



( >rdinary Stamp 

Ornamental Work in Spinning 



P 



Parallel and Screwed Shank Compared ................................... 73 

Peg Stop, on Cutting Bed ............................................... 26'.' 

Per Cent of Carbon in T.x.l Steel ........................................... 5S 

Piercing and Blanking, Successive ....................................... 137 

Piercing, Complete Set of Tools for ................................... '.'3 

Pitch of Press Screw .............. ..................................... :;7 

Plate Face, Setting Work upon a Lathe . . . ................ 245 

Plate, Gauges for Sheet Metal .............................................. 15 

Plate Guide Fixed to Cutting Bed ......................................... 2(51 

Plate, Points Concerning the Dial-feed .................. 1*9 

Plates, Guide and Stripper .............................................. '.'5 

Points, Important, in Press Construction .................................. 1 '-I 

Points, Important, Concerning Dial Feed Plate ........................... I-'' 

Position^ stresses in Press Frame ..................................... 32 

Power Press, Selection of Suitable .......................................... 149 

Power Press, Single Acting ........................................... 159 

Power of Presses and Stamps ........................................ 

Preparation of an Accurate Boring Jig ................................... -41 

Preparing a Standard Die ................................................. 81 

Preparing the Die for Drifting .............................................. '.'1 

Preparing thaPalub ...................................................... f5 

Press and Stamps, The Power of ............................... 

Press, Chief Defects in Single-acting ....................................... 159 

Press Construction, Important Points .................................... 1-M 

Press, Construction of Double Action ...................................... 143 

Press. Double Crank ................. , . ............................. 17 

Press. Double-ended, Tool Changing in .................................... K-9 

1 with Dial-feed Motion ........................................ 1*4 

Press Fitted with Toggle Gear ........................................... 199 

Press Fitted with Holler-feed Motion ........................ 182, 189, and 192 

Press Fitted with Worm Adjustment .................................... 197 

Press, Geared, Single-sided ................................................ 157 

Preas Power. Selection of Suitable ........................................ 149 

Press, Power, Single-acting ................................................ 1 ">5 

Press. Single-acting Open-back ........................................... 161 

Press, The Use of a Stay Bolt mi ....... ................... ....... 153 

Press Tools for Bending Metal ............................................. 123 

Press Tools for Cutting Wire ............................................. l->'> 

Press Tool Setting ................ .......................... -'M 

Press, Work Done in a Copring ......................................... 

Presses for Special Work .." ................................................. 149 

Pressure Plate with Positive Lift ........................................ 163 

Pressure Plate, Adjusting the .............................................. 165 

Pressure Required to Cut Blanks ...................................... 

Profiling a Cutting-out Bed ................................................ 231 

Profilii: 



Profiling Machine, The Use of -'.".' 

Proper Place to Apply the Stop Mot on 1 73 

Punch and Die. [aterobajnM&llty of 79 

Punches and Dies, Hardening and Temiwring -"7 

Punch, Bed, and Stripper, Correct Setting of 



INDEX. 309 

PAOE 

Punch Built up in Sections 67 

Punch, Cutting Angle on 65 

Punch End, Radius on Drawing 129 

Punch, Methods of Fixing 69 

Punch Shank being Screw-cut 221 

Puncher and Dies, Standard 80 

Punches, Attaching, in Double-action Press 145 

Punching and Shearing 61 

Punching and Shearing, Action of 71 

Q 

Quadrant Dividing Headstocks 235 

R 

Radius on Drawing Punch End 129 

Ram, Actuating, Extracting Mechanism 117 

Ram Adjusting by Plates 42 

Ram Adjustment by Worm 197 

Ram, Forces Acting on 51 

Ram, Methods of Driving 41 

Ram, Stop Motion Arranged in 171 

Ram, Unexpected Descent of 195 

Reading the Micrometer 8 

Re-drawing and Drawing 127 

Re-drawing, Tool Dimensions for 131 

Relative Position of Cranks 51 

Removing Small Shell from Drawing Punch 147 

Rivet Head Spinning Ill 

Roller-feed Motion, Advantages of 183 

Roller-feed Motions, Application of 191 

s 

Saw, Hardening and Tempering a Slitting 269 

Screw-cutting a Punch Shank 221 

Screw Press, The Work of a 295 

Screwed and Parallel Shank Compared 78 

Sections, Punch Built up in 67 

Selecting Special Automatics 215 

Selection of Suitable Power Press 149 

Set, Complete, of Piercing Tools 03 

Setting Correctly the Punch, Bed, and Stripper 257 

Setting Extracting Mechanism 11! 

Setting, Necessity of Correct Tool 2il 

Setting, Tool, Troubles Caused by Careless -'53 

Setting Work on a Lathe Face Plate 245 

Shank, Parallel and Screwed Compared 73 

Shaping Machine, The Use of 221 

Shearing and Punching 61 

Shearing and Punching Action of 7 ' 

Shearing Machine for Circular Blanks 17! 

Shearing Machine Details 177 

Shearing Machine, Factor of Safety for 28! 

Shearing Method of Cutting Blanks g 

Shearing, Pressure Required for Iron Bars 2V 

Sheet Metals, Annealing *l\ 

Shell Cartridge, Formation of J* 

Shell, Small, Removing from Drawing Punch I* 7 

Single-acting Power Press JJ 

Single-acting Press, Chief Defects in 10 ' 



310 INDEX. 



Single-sided Geared Press 
Slides, Balanced, Advantage of 



Sliding-key Stop Motion, banners of 

Slitting Saw, Hardening ami Tempering .1 .................................. 169 

Special Automatics. Selecting .............................................. lit 

S]*-eial Form of Drill Chuck .............................................. 101 

Special Konn of Work Chuck .............................................. 115 

Special Machine Vice ...................................................... -:'.:'. 

A .rk, Presses for ................................................. 149 

Sphere, Metal, Drawing a .................................................. 133 

Spinning a Rivet Head ................................................... Ill 

Spinning a Sheet Steel Cup ................................................ ll:i 

Spinning Lathe ........................................................... 110 

Spinning Oj>erations, Kxamples of ........................................ H>7 

Spinning ( irnamental Work ............................................... 109 

Stain j> Block and Hammer, Weight of ...................................... 205 

Stamp Die Boring on Lathe ............................................... -JI9 

Stamp Die Forging ........................................................ 54 

Stamp, Double-tyjK-. Advantages of ........................................ 206 

Stamp "Force" or Top Die ................................................ 59 

Stamp Hammer Raised by Friction ........................................ .' 1 3 

Stain) i Hammer, Work done by .......................................... -'-'.' 

Stamp Operators, Accidents to .............................................. SOS 

Stamp, ( >rdinary Type of .................................................. 204 

Stamping ..... .' ............................................................ 204 

Stamping, a Steel Washer .................................................. 139 

St:ini]i8, The Power of ...................................................... 291 

Standard Cylindrical Gauges .............................................. 18 

Standard Dies and Punches ................................................ 80 

Stay Rod for Strengthening Press ......................................... 31 

Steel, Heating, Uniformly for Hardening .................................. 203 

Steel Washer, Stamping a ................................................ 189 

Strengthening Press Frame ................................................ 83 

Stivti-her, Automatic Umbrella Machine .................................. 103 

Stiipi-ei -and Guide Plates ................................................ 95 

Stripper, Common, A rrangemeiits and Waste Work ........................ 255 

Stop Motion Arranged in Ham ............................................. 171 

Stop Motion, Danger- of Sliding-key ........................................ 175 

Stop Peg Fixed on a Cutting Bed .......................................... 259 

Piercing :>nd Blanking ........................................ 137 

Surfaces, Mensuration of Metal ........................................... --'77 



Tempi-ring and Hardening Dies and Punches 267 

Tempering and Hardening at One Heat 265 

Tern],-, ing and Hardening a Slitting Saw 269 

Test Indicator*, Methods of Applying 289 

Te-t Indicator*. Tviws of Lathe ." 287 

The Bumping Hit ' 27 

.-I space* Compared 34 

.: Limit for Punching f.S 

Toggle Drawing Press 199 

Tool Set f Correct 251 

OanfoM -.'.'.3 

T.-.N, Annealing, in Slaked l.iine 273 



: , .Mgs, Accurately Bo ring L'41 

ion Work ->afi 

151 



f,.r Bending Metal 123 

HI 

<rclng 03 

Tools, Complete Set of Blank-cutting '.'8 



INDEX. 311 

PAOE 

Tools, Changing, in Double-ended Press 169 

Tools, Dimensions for Re-drawing 131 

Tools, Interchangeable 87 

Tools, Machine, and Automatics 215 

Tools, Making Machines Used for 217 

Types of Lathe Test Indicators 237 

u 

Umbrella Stretcher Machine, Automatic 103 

Unexpected Descent of Ram 195 

Uniformly Heating Steel for Hardening 263 

Unreliable Methods of Erecting 46 

Upper Stamp Die 59 

Use of a Stay Bolt on a Press 153 

Use of Profiling Machine 229 

V 

Vertical Hopper for Feeding Blanks 203 

Vice, a Special Machine 233 

w 

Washer, Stamping a Steel 139 

Waste Work Caused by Common Stripper 255 

Weight of Stamp Block and Hammer 205 

Whitworth Standard 6 

Wire Bending, Tools for 121 

Wire Cutting by Press Tools 125 

Work Done by a Stamp Hammer 299 

Work in the Copying Press 293 

Work of the Fly Press 294 

Work of a Screw Press 295 

Work, Ornamental Spinning 109 

Work, Setting, upon a Lathe Face Plate 245 

Work, Tools and Jigs for Repetition 236 

Worm Adjustment for the Ram 197 

Worthless Gauges 3 

Wrought-iron Base on Die 55 



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